I have Real Player and Windows Media Player. Windows Media Player can play all the sound and video files that I need to play but with Real Player I can easily download videos from websites.
Windows Media Player 11 (or the one that comes with W7). Starts a lot faster than Winamp in my opinion.
Winamp was the bees knees back in the 90s, I loved it. I use iTunes. It's big, slow, and bloated - but it works. I tried Winamp + plugins to manage my iPods, but it never really worked out very well.
FLV Player - I use it to watch YouTube music videos. Windows Media Player - I sometimes use it when I'm busy and no time to watch music vids.