Don’t know how I’d missed this before but I was browsing Microsofts list of Genuine Advantage offers and came across this:
Windows Genuine Advantage Special Offers > Offer Details
Media Center Karaoke Plug-in
Media Center Karaoke Plug-in is designed for Microsoft Windows XP Media Center Edition. Media Center users can use this plug-in to select audio channels when playing VCD or DVD, can display lyrics included in WMA or MP3 music files, can remove vocals from the song, can also control microphone connected to the PC. With this plug-in, the user can enjoy Karaoke experience in Media Center using popular audio/video media files, e.g. WMP3/WMA, not necessary depend on special Karaoke media files or special devices.
The following hardware and software are required to run Media Center Karaoke Plug-in:
Windows XP Media Center Edition 2005 or above