I think I have sussed the problem, asked a question on the Netgear forums and someone there suggested pinging between the two PC's.
I was able to ping the Desktop from the laptop but not the other way round.
I only have the free, bog standard Zone Alarm on the laptop and it seems that that is on the blink, when I try to open the GUI it is blank. I will either ditch it or reinstall it. Possibly not really needed behind the router anyway, don't have the Windows firewall enabled on either.
I shutdown Zone Alarm on the laptop and I was then able to ping it and lo and behold could view the folders on it.
Thanks for all the suggestions folks.
Jim.