Slice

For me Nod32 hands down. I have tried many virus killers, and used a few at work. NOD32 has superb speed, very high detection rate, and importantly very low on system resources! Currently at work I use Sophos (slowphos as it's effectionately know in some circles). The resident programs etc take up over 15MB - similar resident protection in NOD32 use around 10MB.

No unticking all options does not disable the damn annoying thing. I have disabled it several times only to have it reactivate itself somehow and pop up at very inconvenient moments. It's almost as annoying as the damn paperclip. NUKE IT FROM ORBIT I say.