This is a good site for demonstrating atleast one way to setup your media center pc to use and share movies with your xbox 360.
Fraggerock Gaming Community » How to Rip DVD Movies to Media Center and Watch Them on Your 360

It is hard to tell if Gamefly is a good service or not.  Since I have joined, I have recieved 2 games and have not yet returned them.  I think the service may be a good thing overall, but there sure are not a lot of Xbox 360 games!  That however, is not Gamefly's fault.

The one thing that has annoyed me so far is when signing up, you can only sign up for a 2 game plan.  You must wait until after 60 days for a 3 game plan.  Why?  They have your address and credit card info.  What do they have to lose?

Well, time to try Gamefly.  Patrick has been threatening to cancel for months, but recently talked me into giving it a shot.  I guess I will see how they do.  I however will cancel if there service is poor.