Client unable to connect to SBS 2003 domain

I am having a pretty hard time trying to connect my client computers to our new sbs 2003 domain, any help would be grateful. I have already configured sbs to be my DHCP but when i try to join the domain from an Xp computer it says domain not found in DNS. I have added the user and the computer in SBS and when i try to run http://servername/connectcomputer it just says page not found. Right now the computer is able to connect to the internet but it will not join domain, and it is on a workgroup now.

Thank you