Originally posted by Edge
Yes you want to install it to your hard drive and any other 360 games you have to your hard drive.
By doing this, you reduce the load times for your game to load, you get faster responses from the game, once the disc drive reads that your black ops disc is actually in your 360 the drive stops spinning and it reads the game off your hard drive.
With this, this reduces how hot your Xbox gets, and extends it's life, as the drive isn't constantly sitting there spinning. Your 360 will also will not run so loud.
There are no draw backs to doing this to your system, only things that will help it, improve it's life, and keep it running.
--Moved: Xbox 360 Questions.
I read somewhere that for halo you shouldn't install it to your hard drive because the game was not meant to be played that way