Ok, thanks Mike-Bracknell. I can see why books are produced for 'dummies'.
I'm trying to connect to the Toshiba as ROB\Administrator (Computer name and User Name) and my password for the admin. account. From what you say that seems to be correct.
I still get the same error msg. I've doubled checked the IP address of the PC and it seems ok as well so I don't know. Perhaps I'll leave it for the time being as I can see the Mac on the PC.