I got Mame to boot of a CD and use ROMS on that cd, I'm not sure yet about configs and wotnot, but I'm assuming I can't (unless I can somehow configure MAME to save this info on E: or F:)
I didn't use XISO but I did use one of those ISO Builders (xboxisobuilder maybe?)
I only played Mortal Kombat but the sound was kind of stuffed
Will keep ya's posted