On the lappy downloaded the SATA Adapter drivers from the MB website, put them onto a floppy, booted up desktop, hit F6, loaded all that then did a Windows repair reinstallation. All working fine. Managed to back up to CD everything of any importance (something I should being doing fairly regularly - learnt my lesson there); Subsequent full CHKDSK which took about 2 hours (240 Gig HDD) found no errors. So hopefully ok now. Bizarrely the only thing I lost was the IE favourites folder (no great shakes - needed a clean out anyway) and the icons on the taskbar just right of the Start button.
So thanks for all the help from everyone, esp TOG
Oggin
p.s. Anyone know how to get back the "Show Desktop" icon that normally resides just to the right of the Start button on the taskbar?