if its downloaded to youre hard drive then youll be fine if the disk can be read.

If its not installed then youll need a new disk

TTGxBruces wrote If I lend my friend MW2 and install in my HD I will be able to Play by booting in my broked Disk?The disk can be readed but when I will go play MP after 5 seconds that I choose a class the disk i unreadable.This will work?

You XBOX needs to be able to read MW2 long enough to install it to the HDD. And yes, it will work.

Great Grammar :p
Even if you install it, it will only help a tiny bit like 10% better. I have a MW2 disc with a small crack in the center and I installed it to my HDD but it's still saying disc unreadable every now and then. I bought a new disc that has quite a bit of scraches on it but no big or very noticable ones. It always will say disc unreadable because, the disc is unreadable Derp. But it does help. And no you cannot boot MW2 from your HDD without the disc. Only on a Jtag/RGH.