Hi Dr Hugh. Thank you for your assistance. I will check out your info - I really don't know anything about mirroring a drive. I have used knoppix to rescue data and partition drives, and also ubuntu before I discovered I had not achieved "dual boot" Guess there is a bit to learn...

Lurkswithin, many thanks for your help, also. Can we explore this a little further, please.
If I "image" the drive with the OS on, would this insulate me against a fatal crash with the consequence of rebuilding the whole XP system again? If so, I am happy to leave the OS where it is and set up the ubuntu to boot from a separate drive. It is currently sitting on the new drive (200Gb partition) but I had to disable the grub (boot) to get back to XP.
Given all of that, how do I: 1. mirror the drive, and 2. How do I set up the ubuntu and the XP (on seperate drives) as dual boot. ??

And, thank you to Status1 for your response.