Hi
I had this issue myself, but a bit of hunting around got me sorted.
1st point - The MS downloaded EPG is NOT the FreeSat one, so it doesn't know about some of the channels - it's also out of date - 108 says it's BBC HD, but that that's the OLD DVB-S service, they moved to DVBS-2 a while ago now..
Also, Channel 4 HD moved from Eurobird to Astra last week which doesn't help either!
So..
You need to manually find the channels:
I'm making the assumption that you know your way around the Settings menu in Media Centre(er) too.
Do a manual transponder scan:
Frequency: 10847 MHz
Vertical polarisation
Symbol rate: 23.0 Mbaud
Should find you BBC1 HD and BBC HD
Do a Google search for Channel 4 HD frequency and make sure its a new post (I can't find it right now as I'm at work with limited internet) and do another manual transponder scan
ITV HD Should already be there.. ch 1270 or something from memory?
Next, you'll probably need to re-assign TV listings as the HD channels will probably only have "now & next" listings (Just re-assign from the SD channels
Then sort the channels into a sensible order..
Honestly, it takes HOURS!! to sort it all out to look sensible, but if you do this, and maybe add some nice idents from MyChannelLogos you'll have a system that looks much better than anything else out there, has more features and is easier to use that even Sky!
Good luck and don't panic, it's all worth it in the end