based on my testing Antivir is probably the best for most users, you can deactivate real time protection in one click if you want it off for gaming. Its detection/removal is as good or better than most paid AV's.
AVG, Avast, Antivir, or NOD32 or Kaspersky are the only 5 AV apps I'd consider.
I like spyware blaster, spybot, AVG antispyware, A Squared, and hijackthis for antimalware apps. I use all of them and either Antivir or AVG for viruses.
Free security apps shouldn't scare you, if you have a good trojan/spyware scanner or two like some of the ones I listed, a decent AV program, check startup entries & new programs, use something like regsupreme or autoruns to make sure nothing unexpected is in your registry, you'll be safe.