Strange case really - up and running again, problem appeared to be 2 things.
Firstly - I had static IP addresses on all my PC's and have now set them back to automatic to get connected.
Secondly - MTU settings. The Belkin router only lets yuo go to 1492, but my main PC is vista which defaults to 1500. Followed a web link or two and found out how to change this. Finally go tconnected. the had to download DR TCP and changed the figure to 1430 on each PC. This eventually got me connected.
Also had the same problem with PS3 again automatic setting is 1500, and wouldn't connect to Playstation Network, by setting this to 1430 got that working too.
My sister uses a single PC and a netgear router, again had to set this to a non static IP address to get it connected, although this didn't have the MTU problem.
I had discussed this with both Orange and Belkin tech support and got no where - seems a bit off that one of them couldn't point me in that direction.