If you’ve got Windows 8 Pro, and wish to add Media Center to it you need a key from Microsoft. In future this wont be free, but you can get one free until 31st Jan 2013 thanks to a Microsoft offer. I have registered for mine, even though I don’t run Windows 8 because I may want to use it in future so why not!
Whilst I don’t recommend Windows 8 generally, for a Media Center PC the UI problems aren’t really relevant. Now the main codecs and plugins, including Media Browser, have Win 8 compatible versions, using Win 8 Media Center should be entirely doable.
“I've been on this hunt a few times myself. I still have my Aluminus ultra in black (only 5 5.25…”