Stupid modem

[Raidien{MEOW}]

If you set yours up anything like mine you will usually need to :P

If you have a web server you will need a static ip... so... when you lose your IP, you have to change the router from static to dynamic, then copy all the info, then change back to static with the new settings (this way if you refresh your modem/router it will grab the same ip), then reset everything again. (not to mention then going to godaddy to change the dns settings)

however, about the mac address... usually that pulls off whichever computer you are accessing your router from... i've never seen where it grabs it from the modem... but sometimes changing that will help  as well...

also, what lights do you get when you connect the modem? does the ready light flash or stay solid?

[Smooth*{MEOW}*]

On the modem, from top to bottom I have: power, pc, data, cable.  Power and cable are constant, PC flashes, and data flashes when I'm loading something.

[THEKATZ*{MEOW}*]

One last thing then I will sit out here. Assuming that your modem is from your ISP.
Your ISP needs a MAC address.  Lets forget the MAC of the modem, that is apples and oranges. They need the MAC address from your ethernet card.  Since you have a router here, your ISP cannot see the MAC address of your computer. (this is what routers do, they hide computers) I can not stress enough that your ISP needs a MAC address.  Not of the modem but of your computers ethernet card.  All ethernet cards have a unique address.  It is pretty much like a phone number.  This is so your ISP can make that connection to your system and allow you to have access to the internet.  No way around this here.
Below is right out of the book for your router.  May be a little different but basically the same as for the MAC address.

Chapter 6: Configuring the Wireless-G Broadband Router
The Setup Tab - MAC Address Clone
Wireless-G Broadband Router with RangeBooster
The Setup Tab - MAC Address Clone
A MAC address is a 12-digit code assigned to a unique piece of hardware for identification. Some ISPs will
require you to register a MAC address in order to access the Internet. If you do not wish to re-register the MAC
address with your ISP, you may assign the MAC address you have currently registered with your ISP to the Router
with the MAC Address Clone feature.
Enable/Disable. To have the MAC Address cloned, click the radio button beside Enable.
MAC Address. Enter the MAC Address registered with your ISP here.
Clone My PC’s MAC. Clicking this button will clone the MAC address.
Change these settings as described here and click the Save Settings button to apply your changes or Cancel
Changes to cancel your changes. Figure 5-16: Setup Tab - MAC Address Clone