Thanks John, I'll see if I can identify the drive - may have to take the machine to pieces to do that!

But what does not seem to be available it information on how large a drive (or partition) I can defrag in W98SE - nor does anyone (it seems) know a freeware defragger that is good. There used to be quite a good paid for one in Norton Tools, but the only Norton Tools I have is for W95!