Thanks guys for the good thoughts.
1. There's only 1 IP - that of my notebook (10.0.0.X1)
2. No reply on pings from 192.168.1.1 (default), 10.0.0.ZZ (the changed IP for the Linksys) - no comms from the Linksys
I might try a new one - disable DHCP on the Speedtouch, and make the Linksys the Router. Will report back...(hopefully!!)