Now I'm not an expert by any stretch of the imagination, but I also happen to have an SMC7004 (mine is the cabled version). The router does allow you to specify the MAC address that it will use when communicating through the WAN port. I know this because I recently had to reload the MAC address from my original computer back into the router so that it would work with Comcast cable (another @Home --> ATTBI --> Comcast refugee). I think you should find the option under the WAN selection of Advanced Set-Up (I'm not at my home machine right now, or I'd look for you).