Here's were you can get it: Windows Media Center 2005 and it also the cheapest place I found for it; unless you can find a cheaper one if you do please post it here!!
http://store.yahoo.com/directron/xpmedia.html it has it for $126.00 US
It also has the real ms mediacenter 2005 remote and ir for $44.00 US
http://store.yahoo.com/directron/xpmediactrl.html
Cheers
Protecteur