Hey, thanks cattletruck! If it wasn't for the advice and encouragement here, I think I would have given up (well, I very nearly did). At first I was prepared to accept just a one way share but I was niggled at the Win 7 to Mac sharing failing. Found that article just in time.
I want to configure the firewall to allow the connection. New to this as well, so be prepared for some daft questions after I've had a gander at the options.....