@Solidus : Well I mean the 360 version is the port. It's slightly expected that it will not look as good as the original version.
Same thing applies to all multiplatform titles. Which is why most PS3 mutliplats do not look as good as the 360 counterparts. (going by the concept most multiplats are developed with the 360 as the primary platform and them ported to the PS3)
The internal rendering resolution of games on the 360 is pretty much a moot point considering that ANA, the scaler chip, is pretty damn brilliant at handling the scaling to native resolution.
I honestly, desperately wish that the PS3 had a scaler chip.