Router Connectivity

It will be one of two things or both - either your computer is not setup for DHCP or your router is using the same IP address as your ISP or both.

To check ISP IP address connect your computer to your modem then: from start => run => CMD (hit enter after this)
a command window opens, type "ipconfig /all" without the quotes.
The line with "IP address" gives you your ISP IP addr.
Compare this with what you get from your router manual if they are the same then do the following:

To configure your computer to use a DHCP IP address, go to the Control panel => network connections => Properties (right click on your default connection) => double click Internet protocol (From general tab) => (a new window pops up) from the general tab ensure that "obtain an IP address automatically" is selected.

To change the IP address of your router check your manual and do the following:
IP Addr => 10.10.1.1
Sub net mask => 255.255.0.0
Default gateway => IP address from your ISP
Make sure to the router is set to act as a DHCP server.

You should be up and running.