What kind of disks would I need to copy a computer game onto another disk?

What kind of disks whould I need to copy a computer game onto another disk? I want to back-up my sims 2 nightlife and university disks but what kind of disk whould I need to do that?How many GB or MB would the disk have to have?What kind of disks would I need to copy a computer game onto another disk?
You could stick them both easily onto a DVD, with lots of space left. But it's not as simple as dragging and dropping. You'll need special software. Just google "CD Backup Tool".What kind of disks would I need to copy a computer game onto another disk?
normally the games come out the are compressed onto a disc so its hard to say, a Cd disc is 700Mb and a dvd is 740 Mb so you best bet is to back it up on an external drive, that plugs into a usb port