Thanks Hugh,
The PC is a Dell Optiplex GX 270 small format, which, according to the manual, is SATA compatible. Looking at the motherboard, next to the IDE sockets, there are two positions labelled as SATA1 and SATA2, one definitely doesn't have a socket to take a cable, the other has a white cover and I can't see whether there is a socket inside it or not. I would have to dismantle the box to get a view of it!
I take it that it isn't just a case of putting an SATA adapter on the IDE cable?
Cheers
Chris