the thing that will save you from all, like, unwanted parasites is a thing called Avast, which is totally free. duuuuude u must be thinkin' it's bad, but no. the free version is just for home users. go to google and type avast, register, get the home version and u r totally safe. (better then AVG and Norton and all those antiviruses, and it's way way cooler, theres like a voice message going "warning a virus has been detected") anyway, this Avast saved me from at least 5 LimeWire viruses. hint - Never download things that have a small size (if u see a game such as warcraft 3 and it says the size is 400kb u can be sure it's a virus) i never open small sized files and i never get viruses, even without the help of avast...

P.S - i never tried to download WarCraft 3 so don't listen to me about that particular game...