You should always install the disc to the hard drive
1) Its makes the system run faster
2) You don't burn up your DVD drive
3) If you somehow ruin your disk,it works most of the time
If you don't know how to do it, these are the steps - From Xbox.com
1) Insert the game disc into the disc drive.
Note: After you insert the disc, the default option is to automatically start the game. If the game starts, exit the game, and return to the Xbox Dashboard.
2) Go to
Home.
3) Highlight the game you want to install with your controller.
4) Press
X on your controller.
5) Select
Install to Hard Drive.
A progress indicator appears while your game is installed to your hard drive. Installing a game to your hard drive can take up to 12 minutes.
Notes
· Installing a game to your hard drive requires between 4 and 8 gigabytes (GB) of free disc space.
· After installing a game on your hard drive, you still need to have the game disc in the disc drive when you start the game.
· Installing games on your hard drive improves load times and minimizes game disc access.
· Original Xbox games can't be installed on an Xbox 360 Hard Drive.