Windows Media Player 11 has been released for Windows XP.
One can also download and install Windows Media Player 11 for Windows Media Center 2005,but to do that one must have Update Rollup 2 for Windows XP Media Center Edition 2005 .It should be noted that the the October 2006 Update Rollup is installed with Windows Media Player 11.
Windows Media Player 11 won’t support any versions of MCE which are earlier than 2005.
Download links of Windows Media Player 11:-
