It used to be that free, or open source, software was worth exactly what you paid for it. Not anymore. There are some excellent "freebies" out there. I always encourage people to support the developers of this software if you try and like the product. Programmers have to eat too!
Listed below are a few of my favorites.
If you want a great little email client, Thunderbird is the way to go. This is put out by the same folks that do Firefox, and is of the same quality. Highly customizable, just like Firefox.
I remember testing MySQL a few years ago and thinking what a pain this database was to deal with. Times have changed. With version 5.0, it can really run with the big boys. I'm not saying run and dump Oracle, but you might want to give this a try. Extremely fast back-end that works great with web applications. The upcoming version 5.1 is supposed to be able to have a scheduler, which is the one thing I really miss from my SQL Server 2000.
Yes, I know, it is a product from the evil empire. But SQL Server Express 2008 is Microsoft's answer to MySQL and all those other open source databases that have been flourishing. And I have to say, they have done a good job. This gets the job done for smaller databases. It's missing a lot of the bells and whistles, but all the security and core of the database structure is there. I've used the 2005 version, this is the 2008 version.
Who needs Microsoft Office? Probably not you. Unless you do some heavy duty coding, this will do just fine. In fact, Writer stacks up as a really nice word processing program. Calc runs everything except some of the heavy-duty VBA coding I do in Excel. The only drawback is Base, which as a database program just isn't up to snuff with the rest of the suite. Give Open Office a try. You'll be surprised. Also check out Solvieg Haugland's blog for some great tips. She wrote the book, literally.
Want a great text editor? Try PSPad. It does far more than I need at the moment. Support for a lot of different formats and languages.
Want a great photo editor? I must say, I haven't even scratched the surface on this one. GIMP seems to do everything I'd need. A little tricky to install, so be sure to read the directions.