You should expect the video to be exactly the same it is now. Unless the receiver is doing something dumb it will simply be taking the information it receives over HDMI, stripping off the audio info to use itself, and sending the video info off to the TV untouched.
HT: Samsung LN32B460 32" LCD (greyscale calibrated) | AVR: Yamaha RX-V765 | L/R: Emp E55Ti | C: Paradigm Center 1 | Rears: Sony Junk | SW: Klipsch RW-10d miniDSP | Sources: Acer Revo Ion running XBMC with mySQL library server and 4 TB HDD, PS3, Technics SL-Q2 TT | 2x Aura Pro Bass Shakers
Bookshelf: Yamaha RX-V992 | Paradigm Mini Monitors
Shelved for now: Paradigm 11 SE Deluxe