The modem/router is a BT Home Hub (which is disabled for wireless and used as a modem by ethernet to the Apple Extreme router, which IS wireless and has an iMac connected to it and that has the cameras...!
Any machine on the home network can see the cameras using
http://192.168.1.274/8000 which is the ip address of the machine they are connected to i assume...
So now i need to work out the rest...
Does that explain it a bit better from my end...?