Mirroring a disk?

I'm desperately trying to mirror a disk for backup purpose. The system is running on one IDE drive, and I want to make an exact mirror before an upgrade. I tried Symantec's Norton Ghost 2003 with terrible result.. The mirror didn't even boot. The system just displayed "GRUB" and nothing more happened. The 2 drives reports the exact same geometry to the system BIOS. Any ideas on how to accomplish my task? Anders Norrbring