I don't realy know the answer but, It turns out his GTA IV was a copy and he had a flashed 360.
He recently purchased an arcade console.
What his question is, If he puts his hard-drive on his flashed 360 and plays GTA IV, then puts the hard-drive on his arcade one, Will microsoft be able to find out it's a copy gta iv. His arcade 360 isn't flashed.
I won't say his gamertag because there might be some sneaky snitches on here
If he gets a good answer he will let me play some more ^_^.