There's a possibility that it does so via hardware controller built into your mb, in which case the procedure I suggested is going to be useless because you are going to create a mirror via the BIOS+Intel (typically) utility that comes with the raid controller.
However, the concept is unchanged: add new drive, create mirror, then break it, then remove old drive.


I got my Intel 80GB x25-m from Amazon.co.uk last May...


... and it comes with the adapter kit. I would assume many of them do.


I think that's very unlikely.



Correct, that was my point actually. I myself have actually gone through many horror stories up to the Vista->7 upgrade. It is the only one that took an entire night to complete, provided me with a very thorough analysis of what was done and how each piece of installed software would behave with the new OS, and worked just fine.
Admittedly, an entire night is a long time. Still, if you let it run and leave, it could be worth a thought.
Actually, I just dislike the idea of the upgrade to a new OS per se. I just tried it out of curiosity, ready to format all and reinstall since that particular install had gone through similar upgrades previously and was moved to new hardware three times, and I figured it was really time not to be lazy any longer and restart from scratch. But I wanted to see how bad the upgrade would be. And after 1 year I am still using that same machine every day happily. It is just fast. 3 GB RAM helped.