What's the best computer security to have when downloading music?

I'm eventually planning on getting a laptop and I'm wondering what is the best computer security that I can have for downloading music (not like iTunes, I"ll be using MP3Rocket)? I'll be getting a lot of music but I don't want my computer to be full of bugs and viruses and slow down my computer. I also don't want it to block me from downloading music. Any suggestions?

computer security???

plz list all computer security program to make my computer realy safe. i mean very safe

computer security!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!?

What is a good, cheap, security system for my desktop that won't make my computer run really slow?