yes, you still need the disk after it is installed. Installing just helps with load times and your xbox wont make as much noise. be careful though, doing this with halo 3 actually slows down online play. not sure if the same is true for call of duty.

You need the disk so you don’t load the game on the hard drive, then give it to your buddy. You have to put in the disk to play the game, the disk is proof that you own the game. @noctowl is right, it speeds up load times dramatically, which is what is was meant for.

All it does is quite youre xbox from sounding like a jet engine.

Takes up a lot of memory though so i wouldnt do it with many games, unless you have the 120GB HD. They take about 2GB.

ShiningToast above is correct! To echo what he already said:

Just to put things into a moral perspective as to why you cannot play a game without the disk even after installing it on the harddrive: that would be piracy.

Think about it: let’s say you COULD play a game without the disk after an install. There would be nothing stopping you from giving the disk the a friend for him to do the same thing. And so on and so fourth.

Support the developers!

Also, Xboxes can be modded to allow games to be played sans-disk, but that does get into piracy territory.