Firstly
to CF
Secondly, have you tried rebooting your Cable Modem (or STB)?
You will need to turn off the power to all of the devices connected and then turn them all back on in the following order:
Cable Modem / STB
Router
PCs
Make sure you leave each device to "settle" before moving to the next one.
Another thing to check is that you can actually get to the router's configuration page (I think the IP address should be 192.168.1.1 for this router, try accessing that page in your web browser and see what happens).
The other thing you might want to check is that any custom security settings you set up on the router have been retained (WEP keys, passwords, that sort of thing). If your PC is trying to supply one and the router doesn't recognise it then this will prevent you from connecting
I would try the above and see how you get on. It may even be worth using the reset button on the router to set it back to the factory settings - that way you can start from scratch and be sure that it isn't a set up problem.