Yes, Xbox probably will look too dark and hard to play with both turned down. I'd recommend turning contrast down like you mentioned, but leave brightness (or black level) where it is or even boost it a little. The reason is that Xbox and PS2 (possibly GC, but I don't have personal experience w/it) have darker black levels than most DVD players, and brightness needs to be a little higher to see the shadow details. I have to turn brightness up by about 3-6 notches on my Mits for the PS2 compared to how I have the brightness calibrated for other sources. I have a customer who said Xbox looked a little too dark after I calibrated his TV. I recommended he raise brightness by about 6 notches on the Xbox input, and it is working well for him.
On my Tosh 57HX93 I typically have my contrast set around 20. When playing Xbox I set brightness from 65 to 85, depending on ambient light. It works quite well this way.
maybe i have mine backwards, but my brightness is 25, and my contrast is 60. i calibrated with DVE adn it looks great for dvds, for good black level but bright scenes are still bright. my xbox looks just fine on it.
maybe i have mine backwards, but my brightness is 25, and my contrast is 60. i calibrated with DVE adn it looks great for dvds, for good black level but bright scenes are still bright. my xbox looks just fine on it.