the opinions will be different.. i personally like TrendMicro.. however, for free ones, AVG is pretty decent
AVG is the best free one around IMO, but I would also recommend Norton Anti Virus which is also very good.
PC-PRO thought that Avast was the best free anti-virus. NOD32 and Kaspersky are good light footprint, paid alternatives.
AVG is god for free antivirus. if you want a good one I would say Mcafee or NOD32 (i was using the former but with some hardware problem I'm using the latter one) Norton use too much resources and not really effective as these 2.
AVG is not even worth trying. Use Kaspersky or NOD32 Also you Lavasoft ad-aware and CCleaner as antispyware, and the inbuilt WinXP firewall
Norton will make your system a bullok cart. Try AVG Professional. I am using it and I never encountered a viral problem.
I use Avast, as long as you keep it updated its very very good! and powerful. And its free of course!
It's been prob at least 3 years with AVG and no problems whatsoever so far, so, free and effective, what more could I ask for?