We have one on order for the lounge as a dedicated Media Center, it's great if you have a few episodes on the pc (my mate has every Scrubs, family guy, south park etc) You just click the file and up it plays, no messing around. Also does freeview digital. When you boot up it acts as a dual OS with XP and Media Centre Edition selectable. To play games just select XP.

The best comparison is a Sky Plus system on a bit fancier, and with a remote etc its brilliant (we have one at the moment but it's his actual PC so isn't in the lounge hooked up to the telly)