I tried that a couple of times, MJ. Then came the plaintive plea "Where's the e-mail with all the bookings details of my holiday and the print-your-tickets?"
I'm resigned to it being a two to three hour job most times - and to needing to use Knoppix and my FAT32 external drive on about one in ten. I use the Windows Installer Repairer on about one in three - and that does a fair job.
Gillian's is the first in a long time that's been so bad it's come down to wipe-and-reinstall the lot. But we get rid of six accounts (all admins) and leave her with two - hers and Admin. And she goes from XP Pro to Win 7.
Jimtherev - you seem to have the same "client base" I do. Mine's Diocese of Chelmsford, Southend area.