Simplistic thread title, great software! I've been a big fan of SPF Pro, but also have a license for Outpost. Being that I'm smack in the middle of a blizzard and bored, I installed it on my XP Pro SP2 box. This is the first version (2.5.375.4822) that I've run that didn't give me any type of snarf. I also replaced my NOD32 (again, snow and boredom) with KAV 5 Pro and removed BOClean. I'm delighted to say that OP and KAV play together very well. I won't go into the feature set here, but it's loaded with useful ones. Looks like SPF Pro will take a nice long rest.