2 servers 1 domain

That's correct, but it still should be in your domain (just like client PCs).

so instead of creating a domain i should just add it to the existing one? is there a wizard for that? they are both running windows server 2003.

thanks

You add a server to a domain just like you add a PC.

Creating a new domain for a single server usually isn't recommended. Besides, you can't add a domain if the server isn't a DNS. On the other hand, the server doesn't necessarily have to be in a domain, but it's easier to control access if it is.

I have one server running dns I would be adding a server just to do faxes but I would put it on the domain so that anyone that has access to the domain can fax out of it. is this not the best way to go about it?

Yes. That's why I said that it should be in your domain.