I found this topic on avsforum -
360 HD-dvd on HTPC. The drive is $200 and connects via USB - the current software is a bit tweaky - the best that has been managed is 960x540 (or whatever that downrez version is). Bluray can output at 1080 on a HTPC - but the drive isn't nearly this cheap. Once the software is sorted out, it might be a great option to get a player for one of the next-gen formats for only $200.