Well i've done some research, and i figured out some games CAN be modded for xbox, here's a link of one of them (GTA): http://www.gtaforums.com/index.php?showtopic=190476

If this can be done to fifa 2007 in xbox... it would help me a lot! i need a few changes for my game, they're almost minimal, the only complicated thing is the stadiums but here's what i'd like (it will just be for the F.A. Premier league):

-Changing stadiums (let's say, for example change Ataturk to Goodison Park)
-Changing some team's kits (changing Middlesbrough kit numbers colour to black instead of white, changing colour huds in some other team's kits, [not many] and finally matching all kit's numbers, example: Portsmouth's numbers are white but the players names are in dark blue, and changing it to gold [original colour] also matching both number and name colour [check Newcastle, Watford, Blackburn, Tottenham.. the colour on their number is darker than the one on their name, just changing the hud to the same colour] and that's it).

It may be much, but i hope it can be done,
thanks.

EDIT: Don't bother on what i want to do to my game, just tell me if it's possible to mod Fifa 07 on xbox?

Please if anybody knows if Fifa 07 for xbox can be modded