This simple trick will help you bypass the “Microsoft Genuine Validation” that takes place during the installation of Windows Media Player 11.
The trick is to install it in parts. Follow the steps below :
1. Download WMP11.
2. Extract (unrar or unzip) wmp11-windowsxp-x86-enu.exe by using extraction tool such as WinRAR.
3. Go to the extracted folder, and execute (run) wmfdist11.exe.
4. Restart the computer.
5. Execute wmp11.exe.
6. Restart the computer.
7. Start using Windows Media Player 11.
source : http://www.mydigitallife.info