I h=downloaded a few game trials of the xbox live marketplace which include Asteroids, Ms Pacman and Galaga.
These xbox games seem completely identical to the origanal arcade games. They even say copyright 1980 or so as opposed to 2009. I was wondering if these are origanal ROM images running on an emulator. If they are, would it be possible to rip them off the hard drive and run them in MAME? Also, would this be legal?
I'm be surprised if it wasn't an emulator, although it's not inconceivable that they were ported.
'Ripping' the rom is probably unlikely, I don't know how possible this is from an Xbox drive anyway, and I'd be surprised if the resources weren't encrypted or premerged somehow.
Assuming you can access the data, I imagine a custom version of MAME could probably run in (assuming it wasn't in the original format, or a standard version if it was) For non-commercial use it might be possible to see this as legal as it wouldn't really differ from viewing other resource files used by the game on a PC.
That said, your mileage may vary, Microsoft could argue that you were only licensed those games for use on the Xbox, although if I was Microsoft I'd be more concerned about the Mame Artwork project guys ripping and stealing the unique artwork, which isn't already freely available online.