Are the graphics for the same game similar on all platforms?

Pretty much all games look better on the PC. The higher level of processing power and larger amount of memory allows higher resolutions (in most cases higher than 720p, and higher than 1080p if you have a good enough monitor), higher levels of anti-aliasing and texture filtering, and better textures. It depends on the computer's hardware specification since each one is different, but a modestly priced PC with a decent graphics card will outdo the 360 and PS3 with ease.

I don't think there's much of a difference between the 360 and the PS3, and the Wii's hardware isn't as good so that lags behind.

The graphics are usually the same between the 360 and PS3 version of a game. There might be minor differences, but you'd have to be actively looking for those differences.

For a game like Rock Band though, I would imagine that graphics are the least of your worries.

In general, the graphics are the samme, sometimes in games like fallout 3, the textures might look better on the 360 than the ps3, or in prototype vice versa. But when it comes to a rockband game... who gives a damn?

In general, the graphics are the samme, sometimes in games like fallout 3, the textures might look better on the 360 than the ps3, or in prototype vice versa. But when it comes to a rockband game... who gives a damn?

DoomZaW

They did some articles at Gamespot comparing games on the PS3 and 360 - if you look at the games side by side, you can spot a few small differences, usually stuff that could be eliminated with a tiny adjustment of the brithness or contrast controls on your TV, if you really cared. Certainly nothing that you would notice in anything but a side-by-side comparison though.

The comparisons articles jackc8 is mentioning can be found in the search results located here, if you'd like to see a more visual approach.