Upgraded to Win7 this week, mainly to stream Freeview to the Xbox, and it's worked out great, except for the aspect ratio. I have an old 4:3 TV, which will have to do for the moment, and it defaults to full screen stretch. I can change the aspect ratio, but I don't know how to get it to stick -- even changing the channel resets it.

I wouldn't mind changing the ratio each time, but my family see it as a deal-breaker:)

Edit: oops, forgot to mention that I've set up the Xbox aspect ratio correctly, and everything outside Media Center looks fine.