Plugged in new modem, cable stops working

[Spook01]

I got a new cable modem, a Motorola SURFboard SB5100 to replace the modem that I leased from the cable co.

I plug the new modem in and the lights start blinking like normal, then when everything stabalizes, i plug in my router and wait for that to finish starting up. Then i turn on my computer and... the internet stops working.

However, if i unplug the new modem and plug the leased one back in, it works just fine.

Does anyone know whats wrong?

Specs if its needed:
Router- Belkin F5D7230-4
Leased modem - terayon tj715
windows xp
NIC- The intergrated 3com NIC on the Asus ANX7X Delux (might of made a typo, but hopefully you know what im talking about)

[Droppyale]

I believe you have to call your ISP and let them know you are changing your modem... I think they will need the mac address of the modem and put it on their system... something like that...

[jmebonner]

You may have to give the cable company the new mac address...

edit: D'oh, beaten by seconds!!!

[Droppyale]

[Uncle Bob]

My cable co. asked for the MAC number And the serial number.

[Spook01]

I have to call them up?

If it matters... theres a sticker on both the router and the modem listing their MAC addresses.

[HeadBand]

yes call them didnt you do that to turn in the old one most places it is like 5 bucks less a month if you have your own