Microsoft should've pushed this more.
Windows Media Centre is an excellent PVR. Take up was poor due to the cost. A decent media center PC with IR remote a couple of HD tuners and a fluid interface will set you back at least £300. That's a hard sell when you can get a box that does 80% of the same stuff for £100 or companies like BT or TalkTalk will throw a box at you for "free".
The other big problem with media centre is that in the UK you can't use it with Sky or Virgin, Microsoft needed to do deals with these companies if media centre was to succeed.
The final issue is that whilst the PVR stuff was very good, the rest of media centre is very poor.
I'm still running the windows 7 version I guess I'll carry on with that until Microsoft no longer support it and the EPG dies. By which time nobody will be watching broadcast TV and there will be something better to use.