That's really great! I hope to be able to test it next weekend. I'm still testing MythTV on Linux right now and I have it tweaked to where I like. Once I try MediaPortal I'll be able to decide which way I want to go. As far as I can tell they are pretty similar.
The main differences are that you have more settings to tweak on MediaPortal when it comes to DVD playback; and building up a DVD database is easier.
On the other hand it seems that MythTV has a better HDTV cards compatibility. I know that MediaPortal dowsn't have as many cards that work well, but they are working on it (the main "problem" being that most of the developpers/testers are european and therefore don't have enought people to test ATSC, that is changing for the better though).
I have heard that when it works MediaPortal's tv features are very close to Tivo, and they're getting better with every release!