I found a UPnP service running on my laptop (a Sony Vaio which was running a Vaio Entertainment Adaptor - something I've never used) which I stopped.
There was no apparent UPnP service running on the Media Centre PC (Where Nevo Server and Client are running) - although there are tons of services running - some obvious and some a total mystery - so maybe there is one which is an "undeclared" UPnP - but I'm damned if I know how to tell.
At one suggestion I found on the net - I enabled the UPnP user interface in "Add/Remove Programs - Windows Components - Network etc." which lets you see UPnP connections in "My Network Places".
I rebooted the media centre PC and when it came up I could see both the Nevo Media Server and Nevo Media Player in "My Network Places" on my laptop - although neither of them was available when I cliked on them, but I have no idea if they should do anything from there as I've never done that before.
Unfortunately the behaviour of Nevo Studio is just the same as before - it will not see either device.
I tried rebooting the laptop, then killing the extra UPnP service then rebooting the Media Centre PC - and I could see the Nevo Server and Player come up in the My Network Places window on the laptop.
Then tried Nevo Studio again and the same problem - I add a new network place and look for either a server or a player to pair and find neither.
I must be doing something wrong, but whatever it is it is not obvious to me.