PSN and XBOX 360 HDD install,Good but not enough?

[Garnett]

matt247 said:
you have the option to install discs on the 360 and you don't have to install all of the discs, you could install 2 of 3 discs if you want.

 

I dont think you can,i think you have to install all the disc,Im not sure i dont have a multi set disc collection.