Wow, thats actually pretty cool, believe it or not I had never heard of it.
I admit I use the linux based solutions (mythTV, MediaTomb) myself for three reasons,
- Free!
- Configurable (Lots of add ons from large community available)
- Feels nice to 'stick it to the man'. (Yes, I'm employed by the man ;))
But I have to say, MediaPortal seems to fulfill the first two. The 2nd one even more as I can leverage my .net skills to code for it.
Doesn't have nearly the 'Wham!' on #3, but we could always port it to Mono :)
Hope you blog about it to let us know what works for you about it, how easy it was to get going, etc. Especially interested in working with HD content.