NOD32...
despite what people say about kaspersky not mattering with alot of ram (i have a decent amount, 1.5 gigs), i still got ALOT more slowdown when i turned it from normal to intensive....which is what it SHOULD be. They have alot of things dummed down and/or not turned on in the begining, which isnt that obtrusive...but with it all at the max, its very annoying and slow.