Is there any way to possibly mod the XNA game studio into helping create backups that will play with out any mods to the xbox360? I'm sure somebody is already trying it? I read that XNA creates a different kind of file (not an XeX) and the xbox will play it, does that have anything to do with the MS digital signature or what ever? If any one figuers this one out let me know something b/c My xbox has broke two disks Fallout3 and Gears of War 2 and theres no way i ll go pay the 60 dollars a piece again.

This isn't possible. You can't package the files on your own, and get them to play on a retail 360. Also the packages don't have any XEX files contained within, so if you were to add a default.xex, it wouldn't even try to load. However, if you were able to get it to load, it would be blocked from running because of the media checks within the XEX.

what about developing a XEXloader using XNA?

the kernal would still need to verify the signature of the xex so no unless you could sign the xex but then there would be no point to this.

Uhm, yes hello JTAG, now what?