It didn't really work for me.
I managed to set up the AEBS better now, but still no true networking.
I can access the USB HDD from the iMac that is connected via the WAN port on the AEBS. But it's not mounted.
I started up my old iMac, and connected to my network. Interestingly, if I search through the folders in the network link of my old iMac, I find the USB HDD and can actually access it!
The old iMac also sees my netbook (identified by brand and MAC address, which I recognise and is correct for the netbook).
When trying to access that netbook, it asks for a workgroup, a user name and a password. No idea why and what those may be. I assume I have to set those up on my netbook?
Then when trying to do software updates on the old iMac, it does not seem to be able to connect, whilst I have safari open and running fine on the same machine at the same time, what's up with that???
In the mean time my new iMac does NOT see the netbook or the old iMac. I wonder why that is?