On: McAfee quarantines svchost.exe on millions of WinX...

[noonespecial]

AVG is good

http://free.avg.com/ww-en/free-antivirus-download

ClamAV for windows is ok too:

http://www.clamwin.com/

Hell, just running housecall once in a while manually can do wonders:

http://housecall.trendmicro.com