You can back up the original Xbox games, follow the simple steps below
There are two ways that you can back up your games, go on to xboxisozone.com and download your game from there, extract it and burn. -OR- you can use Craxtion/Qwix to make a .iso file of your game and burn
Alright, put your Xbox game inside the computer and open up Qwix or Craxtion.
Allow the program to make a .iso file of your game (.iso is an image file so your Xbox can read it)
Then put a blank DVD-R/DVD-RW/DVD+R/DVD+RW and open up your burning program
Now burn you .iso file of your game and put it in the Xbox and it in the Xbox!
To prevent problems with your copied games put your write speed setting at 4X
Not all Xboxes read DVD+R or DVD+RW
Not all copies of your games work