To remove Windows Media Player on any flavor of XP:
"Control Panel -> Add/Remove Programs", then click the "Add/Remove Windows Components" from the menu on the left-hand side of the window. Scroll down to the bottom and UNCHECK "Windows Media Player."
You never *really* uninstall Windows Media Player from a Windows-based system per se, it still loiters around. However, may I suggest Windows Media Player Classic? It's a stand-alone media player that is super lightweight (doesn't take up a lot of memory or CPU), and is so functional, you'll pee yourself a bit:
http://www.afterdawn.com/software/vi...er_classic.cfm
Good luck.