i use bearshare. its free..and its so freaking fast. when i click on a song to download it..and go look in the downloads section, its either at 90% or + or its already done. Bearshare kills limewire in my opinion.
I use limewire, and it is pretty good. I'm pretty sure I've never gotten a virus from it, but I try to limit my DLs off of it just in case. It's good for videos and music alike.