Borrow a copy, install it to the HDD and use your copy to run it. My brother did it when his FIFA disc got buggered.

This is probably the best option.

If anything you can go to Blockbuster, rent it, install it, go back and play stupid and say you rented the wrong thing, and then rent something else.

Think within 3 months of purchase you can get it replaced by the publisher

thats the best thing to do

I don't know how Blockbuster handles these things, but they do know who rented something last so there's a chance it could come back to you if they can't clean it themselves (and don't charge you for cleaning it).

If you do that I would check store policies first.

the same thing happened to my Halo 3, i just borrowed by friends Halo 3 and copied it to my HDD. I just insert the scratched halo 3, and play from the HDD.

Halo 3 should not be installed the hard drive.

You're worrying to much, even if they asked which is very unlikely you just simply say it was there already and the dude workin in the shop didn't check it properly before giving it you. Those sorts of things never end up with you out of favour.

If it's the only way to get it to work, then needs must, and all that.

its the only way to get it to work without costing you any money. but it will cost you some valuble HDD space, especially if you just have a 20gb one.