The Xbox version has emulation problems that result is weird frame rate issues and other bugs. But unless you're an old arcade player, or just really good at the game, you probably wouldn't notice the difference.

Also, if you don't like it you could always sell it on Ebay or Amazon for anAmazon.com: Marvel vs. Capcom 2: xbox: Video Games@@AMEPARAM@@http://ecx.images-amazon.com/images/I/61T56MA445L.@@AMEPARAM@@61T56MA445L.