Installing Windows 2008 Server

I don't understand when you said " update clients to use this as a secondary DC"  Do you mean DNS

Sorry, yes typo, I meant DNS ;)

I'm assuming this is a fresh installation of a domain.  If so, here is a good guide on how to do this:

http://www.elmajdal.net/win2k8/setting_up_your_first_domain_controller_with_windows_server_2008.aspx

Once you have the domain controller in place, turn off your DHCP on your network (if you have a router / firewall handling it), then enable it on the domain controller.

http://www.windowsreference.com/windows-server-2008/how-to-setup-dhcp-server-in-windows-server-2008-step-by-step-guide/

Once that is complete, restart the workstations, do a ipconfig /all and see if they are pointing to the DC for DNS and DHCP.  Once the clients are pointing to the workstation, join the PCs to the domain.  You will have to create the AD accounts also.

To add to the above.

Here is a full guide on the procedures.

https://www.experts-exchange.com/questions/23665224/Windows-2008-Server-Migration-From-Server-2003.html

If you are going to Windows 2008 Server R2 read link below as well

https://www.experts-exchange.com/OS/Microsoft_Operating_Systems/Server/Windows_Server_2008/A_3644-Windows-2008-Server-R2-adprep-adprep32.html

No, It's not a new domain.  I already have a windows 2003 sever which is a DC and DNS server.
This will be a second DC 2008 DC i will be installing.  I just wanted to know what to do first.

Look over the links this will provide you with the steps

>>This will be a second DC 2008 DC i will be installing.  I just wanted to know what to do first.

As I said in my first post, this is covered in steps 1 to 4 in my guide.

Got it.  Thank you demazter

On the money.  Thanks again.