[jem]

One piece of advice, do a divide and conquer approach to it.

1) Make sure the internet connection works fine without the router in place.
2) Attach the router via a wired connection to the PC and cable modem and check internet connectivity again
3) Set up the wireless without encryption and mac address restrictions and check again
4) Finally set up the encryption; WPA2 PSK is the best option if all your gear can support it and lock access to specific mac addresses (although option differs as to the usefulness of the latter but it can't do much harm).

Wireless can sometimes be a bit of a black-art. It tends to either work or doesn't and when it doesn't work it can be a real pain to fix. By staging everthing at least you'll know where it went wrong.

John