Winamp.

It's awesome. I can't imagine using anything else. I especially like monkey-proofing my desktop with specific band playlists so my friends won't whine about not being computer literate enough to work Winamp. I would use Windows Media Player but it messes with the way I have my taskbar setup (I have it set to be 3 bars high, and everytime I use Windows Media Player it sets it to 2 bars). Plus I haven't found an mIRC script with WMP support.