I'm going to suggest something else
I also had the same decision to make when i built my media center pc. What I ended up doing is using W7MCE for Live and Recorded TV and XBMC for everything else. For me it seems easier especially since XBMC supports pretty much everything. Also its a self contained application which doesn't require you to hunt down codecs, splitters, muxers and plugins for MCE. It has pretty good support for metadata. It plays ISOs native. There are also GPU accelerated version of XBMC.
I use both and very happy with results as my W7MCE is stock with no additions to it to break things. I also programmed my Logitech remote to exit out of MCE and start XBMC so I don't need to use keyboard/mouse
Something to think about

I also had the same decision to make when i built my media center pc. What I ended up doing is using W7MCE for Live and Recorded TV and XBMC for everything else. For me it seems easier especially since XBMC supports pretty much everything. Also its a self contained application which doesn't require you to hunt down codecs, splitters, muxers and plugins for MCE. It has pretty good support for metadata. It plays ISOs native. There are also GPU accelerated version of XBMC.
I use both and very happy with results as my W7MCE is stock with no additions to it to break things. I also programmed my Logitech remote to exit out of MCE and start XBMC so I don't need to use keyboard/mouse
Something to think about
