Using windows server 2003 with one network card

I have windows server 2003 enterprise, with one network csrd, a linksys wifi router, internet connects to this and all computers including server. Currently, my router is handing out ip addresses and dns, but i want to switch dhcp and dns to my server and run AD on the server. I got it to work successfully but when i try to add a computer to the domain i get: error cannot find dns record or something similar i cannot remember. If anyone knows a tutorial or any knowleadge on this, please share.