I don't like having too many players on my PC personally, prefer saving both diskspace and desktop space, not to mention resources.
I myself run Media Player (or classic, never both on my pc, classic is much cleaner tho), Winamp for my music (like the way how you can make mp3 lists and all the extra's it has like winamp broadcast) and for DVD movies I prefer Power DVD (has some nice features for playinga DVD movie).
But a player alone isnt enough, so I also use codecs like: KLcodec pack full, Real Alternative and Quicktime Alternative (as I don't like the adware in real and quicktime)