Re: Question on freebies on this list
The only software on that list I use regularly is Avira, which is my primary anti-virus protection on this computer (running Vista). It seems fairly robust. As noted on that page, you can get a free version of AVG that's pretty good. Other than that, I'm also a believer in Ad-Aware Free from LavaSoft.
One can also sharply reduce the odds of encountering malware by avoiding the seedier corners of the net...and by running Linux.