Macbook won't connect at 1Gbps

I tried to connect my MacBook to one of the ethernet ports on my AEBS, but it won't connect if I manually select the speed as 1000BaseT in System Pref > Network > Ethernet. I have two PCs with gb ethernet connected to the AEBS, and these work fine; XP reports the connections as 1Gbps. The MB works fine at 100BaseTX.

I have not yet upgraded my cabling from CAT5; could this possibly be the reason why my MB won't connect at 1Gbps? I am running v 7.2.1 on the AE.

Message was edited by: wurz72