Hey Just wanna ask? Are all those tools/software spamfree? But anyway thanks for sharing...
From a brief look many of the applications recommended in the original post are legitimate and spamware/spyware free. I've personally used many of the Anti-virus and anti-spyware tools over they years and they're all excellent. Picasa is a Google product and a very good photo management program for home users and I've run into GIMP before in the open source community.
However many of the applications available at download.com DO have spamware and spyware. In fact I know that many of the applications in their top 20 are rife with malware, so avoid that site if it's a concern for you.
As for other free software to throw in the ring, you can try http://sketchup.google.com/index.html
which is a very good CAD system and one of the few you can use for an unlimited amount of time for free. The only practical limitations of the regular version vs the pro is the ability to save to other common file formats used by Bentley and Autodesk.
Also, if you ever find yourself wishing you could control a computer in another room remotely, or your home PC from work you could check out [url=http://www.teamviewer.com/index.aspx]TeamViewer[/quote] which allows you to completely control another PC from anywhere. It doesn't even require installation so if you don't have permission to install software on a system you can still use it, very useful when using public computer say at a library. It's 100% free for home use.
Oh, and lest we forget http://www.google.com/google-d-s/tour1.html
. Completely free, compatible with MS Office and OpenOffice applications, but has the advantage of being completely online, so you can access your documents and can easily share and collaborate with others instantly. Personally I think this software will take over from MS Office as the market leader in productivity software in the next decade or two just because of the ability to collaborate in real time on documents.