Crack open the plonk, i've got it working!
This is bizzare how i got it working, i've tried a couple of different variations and this is the only way so far.
1) switch off mac, pc +cable modem
2) switch on modem
3) switch on pc and connect to web
4) unplug pc from modem and plug in network hub and mac
5) try to connect mac, when the error message crops up plug in pc
6) wait five minutes (go put on kettle and make nice cup of tea, loverly)
7) refresh safari and voila! internet access.
it seems the pc sets up the connection then the mac piggy backs the connection but the downside is the pc gets booted off the connection and wont go back on until i shut down both machines and the modem.
Off to PCworld in the morning to buy a router methinks, to see if that works better then that mess of a runaround above.
A big thanks to everyone who suggested erm... suggestions. Now i just need a big stick to destroy all this hardware and take the pain away.