Dallinor on 16 April 2009
In my opinion, graphics for a game like Rockband hardly matter. Rockband is all about the supurb audio and gameplay.
The PS3 does (apparently) have an advantage in the audio and online departments, so weight up how important those factors are for you in comparison to the price difference.
Most importantly though, as I'm sure you wont just be playing Rockband alone, take a look at the present and future game library's both systems have on offer.
You have already mentioned that you think you might prefer the Wii's library. If you're certain about that, I think the Wii is the choice for you.
