I must admit that I've kind of looked at Media Centres from afar up till now. The thought of building a PC suitable for keeping in the lounge and then nailing a copy of Windows Media Edition onto it has never really floated my boat (especially not I have my DVR up and running). I'm assuming Apple has a Media Centre solution as well, but again, its not something I can pontificate on...
However, I came across a Linux Media Centre demo the other day and I must admit it's very, very impressive. As I say, I'm not in a position to compare and contrast it to the Windows or Apple alternatives, but if you have the desire for a Media Centre I can only recommend at least having a look at a video of it in action here.
LinuxMCE runs on Kubuntu, and it free. It also does home automation...maybe I really do need a new PC after all...