I'll give a small plug to one vendor. If you're looking for photo quality screen shots check out officialpix.comhttp://www.officialpix.com/
These photos are absolutely stunning. I grabbed two for my buddy's kids and ended up getting 10 more for my boy's room.
All photos come with a matt finish with the acception of the metallix ones which are glossy with a very light metallic looking border.
I got mostly 8 x 10 with a couple of 11 x 14s. IF you're doing a room theme like we are the smaller ones are better since you can get more. We picked 2-3 larger ones just cause they are just too cool.
The prices are pretty good too, only $4.99 for an 8 x 10.