Fighting With Hardware

Setting up a brand new machine, and I get hung up on the simplest part.

I can't get Windows Server 2003 to get an IP from my router, using DHCP. In fact, even directly plugging the machine into the cable modem, there's no IP address. 

Strange thing is if I bring the machine to work, and boot it up, it gets an IP just fine... wierd....

Update: the problem ended up being that the net card was set to auto-detect rather than Full-Duplex, and got choked up and chose Half-Duplex by mistake... wow...