This how to will show you how to install Windows Media Player 11 to Windows XP and bypassing the validation check.
You must do the follow:
Unrar the mpsetup.exe somewhere.If you choose the default destination, you will get a folder named mpsetup.
In mpsetup folder you will see wmp11.exe wmfdist11.exe umdf.exe and wmdbexport.exe. Install them and then Reboot.
Run any media player shortcut you have on your system and a screen will popup asking "express" or "custom"
Choose custom and you are OK.