I use none right now. My laptop screwed over so I have to use my mom's laptop until my sis goes away for college(then I get to use her's). When my laptop still worked, though, I used Limewire. I'm not sure if it screws up your computer, but it certainly downloads well.
How do people get Limewire Pro besides buying it? I just saw that my sis's comp has Limewire Pro. I heard that it doesn't screw up your computer and it's way faster.