I started off using Napster as i'd imagine alot of users did, then I swiftly moved onto kazaa but it had alot of spyware and viruses for me. The next application I used was shareaza (a combination of several networks) however this proved buggy and often ended up crashing.

My current p2p of choice is limewire, it's very good but it occasionaly freezes my computer!

What's yours?