I use Avalaunch, lots of options, downloadable backgrounds right off the dashboard, support for boost mode with qwix, etc.
But almost any dashboard will do if you just want to start games located on your hd... a friend of mine use nexgen (hum, i think that's it), it looks like the ms dashboard and has direct access to the save games, just like the ms dashboard, something avalaunch doesn't seem to have unfortunately. That's one thing I don't like about avalaunch, that and having to go in the settings to check the cpu temp.
And about the media center "shit", it's just another program you add in a folder, any dashboard will run it also. I wouldn't call it shit though, I play almost everything but VHS with my xbox now, dvds, xvid, etc.
Oh and I like the setting in the dashboard where you can set the color of the power led, I put red instead of green ;)
Moon the world