Upgrading to server 2003

I have a Windows 2000 network running AD. It’s two servers running DNS and WINS. One server has DHCP the other has DHCP disabled. I also have two standlone Windows 2000 servers. I would like to upgrade one of my standlone Windows 2000 servers to server 2003. They are all on the same domain and sub net. Is this pretty straight forward ? or am I suppose to do my domain controllers first ? any suggestions/thinks to watchout for would be appriciated.