Hi,
Thanks for the reply. I managed to find what I needed by googling as you suggested.
I first performed a reinstall, which of course didn't solve the problem.

After rebooting with the installation DVD for the second time (holding down the "c" button during the boot), I followed the instructions for resetting his password. Just as I should have done in the first place.
He now has problems with the keychain, but I can sort that out on the next visit.
I converted to OSX a year ago, and have never had to do this, hence asking the question. It makes you realise as a PC owner just how acustomed you become to the reinstall procedure, as my dad had to do this so often with his previous beast.
Thank goodness he is now on a Mac.
