This DOES NOT work that easily with any version of Mac OS X unfortunately. You can't copy the OS X System folder anywhere and expect it to work because of permissions, hidden folders, etc.

You can make a disk image of your hard drive using Disk Utility, and then at any point in the future, you can use this image to restore the hard drive back to when you made the image - OS X and all. To do this with a CD or a DVD, there will be additional steps including reducing the size of the image and making the disc bootable.

May I suggest getting an external USB or FireWire hard drive and storing a disk image of each Mac on this drive? You would then be free to restore the Macs from these images at any point in the future.