A while ago I had an idea to build a mythtv box and even went as far as buying some EPIA based hardware for it. Anyway, life intervened and I never got it working to my satisfaction. Since my TV chose this week to die, I'm presently installing ubuntu gutsy on it with a view to getting it to record programmes from Freeview (should I wish to watch anything on my laptop). Yes, I have the BBC iplayer, but it doesn't get everything I want to watch.
Installing Ubuntu takes a surprisingly long time and is rather difficult when you're on a machine that doesn't have a CDROM.