Help connecting new computers to domain

I have a Windows 2000 server that has been running for god knows how many years (praise Dell for such great products). Recently, I have been put into the server manager. I was told to hook a brand new Windows 7 Professional computer to these Win2K servers. So I got to the Workgroup/domain thing, type in the domain name (marder.com) get an error that the AD DC has a problem. I then try just marder, get a username/password field, enter administrator and the pass, gives long DNS error ending with some directory thing isn't doing something with the child and then it just says .com . Baffled, I clone one of the old XP machines, disconnect from the domain, reboot, go into the administrator account, try to join the domain marder.com but can't. It gives the same error as the Win 7 computer. marder as the domain gives username and password fields but the same result as the Win7 computer too. So I need to know what I am doing wrong. I have gone into the server and added the new windows 7 computer to the computers list in the server. I have not added any usernames or other details. Please do not advise on the XP machine. I was only using it to state the overall problem, not a second thing that needs fixing. There are a few other computers in the office that are connected to this server so it does work.

So I need help connecting a Windows 7 Pro computer to a Win 2k server. I have the right domain, the right admin login stuff, and I have added the computer to the domain list (on the server). What am I missing and why can't I connect with any new computer.

It would be helpful if you would post the DNS error. I don't believe there is anything wrong with the Win7 workstation or how you tried to join it to the domain. According to what I am seeing here you are not getting the proper DNS resolution for your domain name which is why it isn't procceding. FYI .com is the root domain of the server with marder being the child that has the error. Also you do not have to add the computer to AD on the server first. If you log on to the workstation as an admin and join the computer to the domain it will be added to AD during that process. I'm assuming all workstations are running off of DHCP as well?

Lets see the DNS error in full then maybe we can sort this out.