[quote:kfr9anei]Virus scanners mostly go for viruses and not code like deleting files in your system32 folder.
Actually, if you're paranoid about this, Vista is actually a good operating system to go for! I know it's pretty unpopular, but on Vista applications don't have access to any of your personal/system files on disk, and you'll most likely get a UAC warning if it does attempt anything suspicious. Personally, I'm happy with XP though.