Thanks for the tips equill.

I did get the iMac gong by re-blessing the system folder, it also had two systems installed!! and it still has problems with cross/linked files - as the previous owner must have had an external drive connected at some time.

So I'm thinking of starting afresh, but my ultimate aim is to add more ram and install OS X.

Does anyone know if I can install OS X from scratch as most of of the install guides seem to suggest that you must have OS 9.1 installed first?

As a footnote I think it has already had the necessary firmware installed.