Not only was all of the software free, every piece of it was open source, which means that the code is peer-reviewed; no spyware here!

What follows is a list of thirty pieces of software that are the cream of the crop of open source software for Windows. Not only is every piece of it free, almost all of them directly replace expensive software packages.

Now, if only there were an open version of The Sims 2, I might go the whole way and switch to Linux…

1. Firefox
http://www.getfirefox.com/
Replaces Internet Explorer
If you haven’t switched to Firefox for your web browsing needs, do it now. It stops annoying popups and it has tons of amazing plugins that can make surfing the web even better. I could evangelize all day about Firefox, but one thing’s for sure: the first thing I do on any new Windows machine is run Internet Explorer just long enough to download Firefox.

2. Thunderbird
http://www.mozilla.org/thunderbird/
Replaces Microsoft Outlook or Eudora
Thunderbird is an email client that has five big things going for it: it’s free, it’s full featured, it’s lightweight and runs quick, it has an unparalleled spam filter, and it protects you from those ridiculous phishing attacks by clearly indicating which emails send you to a bogus website. If you’re not already using a web-based email solution, Thunderbird should be your client.

3. Sunbird
http://www.mozilla.org/projects/calendar/sunbird/
Replaces Microsoft Outlook’s calendaring functions
Might as well get the Mozilla trifecta out of the way by mentioning Sunbird, which is the Mozilla Foundation’s calendaring program. It’s extremely easy to use (I figured out everything I needed in a minute or two) and easy to share your calendar with others. I consider a calendaring tool to be essential if you’re using a laptop, and this is no different.

4. Abiword
http://www.abisource.com/
Replaces Microsoft Word
Want a good word processor but find Microsoft Word too expensive? AbiWord is my favorite replacement for Word. It’s lightweight (meaning it runs quickly) and includes pretty much every feature that I use regularly in a word processor, plus it can save files in formats that you can exchange with Word and WordPerfect users, plus open any of their files, too.

5. OpenOffice
http://www.openoffice.org/
Replaces Microsoft Excel and Microsoft PowerPoint
If you want to replace the rest of the Office suite, your best bet is OpenOffice. It includes very nice replacements for Excel and PowerPoint (and workable replacements for Access and other Office elements). In fact, I actually prefer their Excel and PowerPoint replacements to the real thing.

6. ClamWin
http://www.clamwin.com/
Replaces Norton AntiVirus or McAfee
ClamWin is a slick anti-virus software that’s quite easy to manage and is unobtrusive while keep your system free of viruses. That’s pretty much all I want from a package, so why pay money for McAfee to keep bugging me all the time?

7. Gaim
http://gaim.sourceforge.net/
Replaces AIM, Windows Messenger, etc.
This is a very clean instant messaging program that allows you to be on AOL Instant Messenger, Windows (MSN) Messenger, and Yahoo Messenger simultaneously with one program. There are other free packages that do this, but Gaim is stable and clean and simple.

8. BitTorrent
http://www.bittorrent.com/
Original but essential
From their website, “BitTorrent is a peer-assisted, digital content delivery platform that provides the fastest, most efficient means of distributing, discovering, and consuming large, high-quality files on the Web. Our mission is simple: to deliver the content that entertains and informs the digital world.” In other words, BitTorrent allows you to download large media files and also use your bandwidth to help others download these files. Search for media files you want and download ‘em.

9. GIMPShop
http://www.gimpshop.net/
Replaces Adobe Photoshop
This is a version of the GNU Image Manipulation Program that does a pretty solid job of imitating Adobe Photoshop - a regular user of Photoshop (like me) can adapt to it quite quickly. It’s very richly featured and runs quite well - in fact, I see no reason to ever go back, even if Photoshop were free.

10. Gnucleus
http://www.gnucleus.com/Gnucleus/
Replaces LimeWire, BearShare, etc.
Sure, LimeWire and BearShare are free, but why not just get the same basic software without all of the spyware? Gnucleus is pretty much identical to those software packages - but without all that extra junk that slows down your computer.

11. VLC Media Player
http://www.videolan.org/vlc/
Replaces Windows Media Player, Quicktime, RealPlayer, etc.
If you get tired of having tons of media players on your computer, get this package that runs pretty much every media type you’ll run across without breaking a sweat.

12. Juice
http://juicereceiver.sourceforge.net/
Unique but essential
Juice lets you effortlessly subscribe to podcasts, organize them, and listen to them at your convenience. In conjunction with PodNova, I find it easier to use Juice to organize podcasts than using iTunes itself.

13. Audacity
http://audacity.sourceforge.net/
Unique but essential (for some)
If you’re interested in recording your own podcast (or just want to make your own voice recordings for whatever reason), Audacity and a microphone are pretty much all you need to get the job done. I’m not much for podcasting (let’s just say I don’t have a radio voice), but I use Audacity for other voice recording purposes.

14. RSSOwl
http://www.rssowl.org/
Unique but essential
RSSOwl is one of many open source RSS readers. In other words, it enables you to use one program to keep track of the content of a lot of different blogs; if you read a lot of blogs, it’s the only way to keep tabs on all of them without devoting hours jumping from site to site. If you have a laptop, it’s preferable to using sites like Bloglines, but if you’re on a desktop, a web-based feed manager might be better.

15. Filezilla
http://filezilla.sourceforge.net/
Replaces WinFTP
Many people occasionally have a need to FTP files to other computers; if you ever have the need to transfer files in such a fashion, FileZilla will do the job slickly and quickly.

16. Keynote
http://www.tranglos.com/free/keynote.html
Unique but essential
Keynote is basically designed specifically for the task of taking notes on a laptop. If you ever find yourself in a meeting or a presentation with your laptop open and want to jot down notes and organize them just a bit, Keynote is unquestionably the program for you. It’s not good at quality word processing, but that’s not the point. In my professional work, I find myself using Keynote almost as often as any other utility.

17. MusikCube
http://www.musikcube.com/
Replaces iTunes
If you’re not already committed to downloaded music from the iTunes Music Store, then MusikCube is the best choice available for a music organizer and player. It organizes your mp3s, makes it really easy and really fast to find them, and allows you to make some incredibly clever smart playlists.

18. Handbrake
http://handbrake.m0k.org/
Unique but essential
Handbrake enables you to stick a DVD in your DVD drive and have the contents of that film stored to your hard drive in a form that can be read by pretty much any media player. I often use it to put a few movies on my laptop for travel purposes, so I don’t have to worry about keeping track of DVDs while on the road.

19. X-Chat 2
http://www.silverex.org/
Replaces mIRC
X-Chat is a free IRC client. For those unfamiliar with IRC, it’s a place for technical people (and, as my wife loves to point out, nerds) to meet and discuss topics in an open environment. I often find it very useful when piecing through difficult technical issues.

20. KeePass
http://keepass.sourceforge.net/
Unique but essential
KeePass is a program that securely stores and manages the abundance of passwords we all use on a daily basis. I have literally hundreds of usernames and passwords spread out all over the place; KeePass keeps them all for me and keeps them safe.

21. TrueCrypt
http://www.truecrypt.org/
Unique but essential
TrueCrypt enables you to convert a memory stick into a strongly encrypted data storage device, meaning that you can store personal data on it without worrying about losing it and having personal information get out and about. I use it to keep some of my most personal data off of my laptop and strongly secured, just in case.

22. PDFCreator
http://sourceforge.net/projects/pdfcreator/
Replaces Adobe Acrobat
PDFCreator creates a virtual printer on your computer that, if you print a document to it from any program, creates a PDF of that document that can be read on any computer with Acrobat Reader on it. After installing PDFCreator, all you have to do is print like normal and out comes a PDF!

23. Freemind
http://freemind.sourceforge.net/
Unique but Essential
Freemind is a “mind mapping” software program. In essence, it enables you to brainstorm and link together ideas quickly, creating “maps” of concepts similar to what you might do on a whiteboard. I find it incredibly useful when putting together ideas for new posts or planning small projects or assembling the backbone of a writing project.

24. NASA Worldwind
http://worldwind.arc.nasa.gov/
Replaces Google Earth
WorldWind is very similar to Google Earth in that it allows you to browse the globe. While it isn’t strong for creating maps (but why not just use Google Maps for that?), it is utterly incredible for viewing three-dimensional landscapes of any place on earth.

25. Notepad2
http://www.flos-freeware.ch/notepad2.html
Replaces Notepad
Notepad2 is a replacement for the traditional Windows Notepad that just adds a few sweet little features: multiple documents; line, word, and character counts; and some highlighting of tags. In fact, I’m using Notepad2 as I draft this post (after using Freemind to organize it).

26. HealthMonitor
http://healthmonitor.zucchetti.com/
Unique but useful
HealthMonitor enables you to keep an eye on the health of your computer. It identifies slowdowns and other system issues quickly and lets you know (for example, it gives a popup if your system memory gets to a certain percentage of fullness, or if your hard drive has only 10 GB free). This can keep you out of trouble and also give you clues to problems your machine might be having.

27. Workrave
http://www.workrave.org/
Unique but useful
Sometimes late into a writing session, my wrists get sore from too much repetitive movement. Workrave basically jumps in before this happens and locks down the computer for a while, preventing me from working too much and causing repetitive stress injury. Since I’ve started using it, it hasn’t significantly hurt my productivity at all and my wrists are thanking me!

28. GanttPV
http://www.pureviolet.net/ganttpv/
Replaces Microsoft Project
If you do any project management (or have a need to dip your toes in the water), GanttPV does a brilliant job of managing the task quickly, easily, and freely. If you need to move to MS Project later, you can export from GanttPV to Project, but once you start digging into GanttPV, you’ll likely have no reason to use Project.

29. GnuCash
http://www.gnucash.org/
Replaces Microsoft Money or Quicken
GnuCash is a slimmed-down version of the bloated Microsoft Money and Quicken packages, but it contains all of the features I want for managing my money. The interfaces are incredibly simple - it functions much like a checkbook ledger on your computer - but there’s a lot of meat hidden throughout the software.

30. True Combat: Elite
http://www.truecombatelite.net/
Replaces Quake IV, Halo, etc.
After all this downloading, you’re going to need to blow off a little steam, and I’ve yet to find a more enjoyable free game than this one. It’s basically a third person combat game, but the graphics are spectacular and the game is quite engrossing.

If you’ve downloaded and installed all of these, you’ve got access to all the productivity software you’ll likely need, clean and open and best of all free.