This may be fairly straightforward... In anticipation of Uncharted 2, I borrowed my friend's Uncharted: DF disc and am about a third of the way through. Unfortunately, he wants the disc back to trade in for Uncharted 2. Now, assuming I go out and buy a used copy online, will I be able to pop it in and continue from my last saved game, despite it's a different disc? I would think the answer would be yes, but this proved to be not the case with Burnout Paradise (though I switched from the disc to a downloadable version of the game...).