ok, I'm not sure which version of the 360 people owns here, but if you got the space, I strongly suggest you install the game on the hard drive.
The unreal 3 engine always seems to work in a strange way when it comes to textures on the 360. (Unreal tournament 3 and more of all....LAST REMNANT which is unplayable if not installed)

the best exemple will be the normady when it docks.

I just thought I would mention it since you did not have the option to install when the game came out.

The game is one of the biggest once installed tho, I warn you
It takes 6.8G of space. (added to the rather bulky saves and add ons...elite for the win!)
To compare 2 games to it, WET takes 4.3G and tales of Vesperia takes 5.9G

Advantages
-Faster loading times
-Better texture mapping.
-Your optic reader will adore you since it is less working, requiring less ventilation.
-less noise from the console

Disadvantage:
-If you have the original 20 G hardrive like I have as a back up 360 (hey, come on, got it on day one and never got ring of death...I ain,t parting with that old thing) it might be a bit heavy on you.
Even for the 40G HDD that replaced the original 20G on the pro (which is no longer manufactured)

If you need help installing a game, I reccomand not setting your 360 to autostart when disc is in" option.
Press Y on the game and the "install to hard drive " option will be there...
it requires about 5 mins or so of installation
I have over 60 games and I always keep my main games installed

(Hey, if you played Metal Gear solid 4, it is nothing, right? As funny as it was the first time to see Snake smokes about 10 ciggiesit's getting OLD!)