WD-52525, Directtv HD Configuration

New to this board, question on configuration. I've got the Mitsu WD-52525 (love it) and the Samsung SIR-TS360 HDTV receiver, hooked up via DVI/HDMI cable. The TV's native resolution is 720P, and the receiver has multiple output choices (480i/p, 720P, 1080i). Do I output all signals at 720P, or at the resolution they come into the receiver at? It also has the option to output 480i/p to that resolution, and force HD signals to 720P or 1080i. What will give me the best picture?

Thanks!