Useful software for windows. Most of them are free to use.

www.pandasoftware.com/virus_info/spyware/test/#
Scan your computer for spyware and Suspicious files online. Very good.
Require Internet Explorer to work.

www.oldversion.com
Old versions of some popular software. Only freeware and shareware. This can be handy if you think the latest version is too big or works bad.

www.snapfiles.com
www.download.com
www.freewarefiles.com
www.freewarehome.com
www.newfreeware.com
www.onlythebestfreeware.com
www.tucows.com/windows.html
Good places to find useful software. Both freeware and shareware.

freeware.it-mate.co.uk
ftp.sunet.se/nonags
All software here are completely free.
 

www.kidsfreeware.com
Many free programs for kids.

www.versiontracker.com/windows
Keep track of the latest version of your favorite software.

jalbum.net
Web photo album generator. Publish your pictures on internet with this easy to use software.

www.skype.net
Call anyone in the world for free. Computer to computer by internet.
Also you can call from computer to a phone for only 2 cent/minute.

www.graphcalc.com
A very competent calculator with a graph function.

mathomatic.orgserve.de/math
If you ever want to solve a symbolic equation or study math you have use for this software.
It's like Mathematica but much simpler and cheaper.

sourceforge.net/projects/guliverkli
A good replacement for the Windows MediaPlayer 6.4 without unnecessary features.
Can show subtitles.

www.openoffice.org
A good replacement for Microsoft Office.
 

www.ragtime-online.com
Ragtime Solo is a complete layout program free to download.
With a layout program you can do your own magazines and printed matters.

www.gimp.org/windows
A good replacement for Adobe photoshop.

Sygate Personal Firewall
A firewall to increase the security in your PC. In Windows XP SP2 there is a builtin firewall.
With Sygate personal Firewall you get increased control of what happens in your computer.