You can't forward ports to a computer in the DMZ - choose port forwarding or DMZ, not both. (Some routers ignore port forwarding if the destination IP is in the DMZ - most don't.)

"computers that are members of the domain are sent directly to the router login" When connecting to which address? 192.168.0.1? The server's internal address? The external address?

"how do the queries to this ip get forwarded to the router?" No forwarding at that point in the process - the router's IP address is the one your ISP gives you, so the requests go to the router. It's how they get from the router to your server that's the problem here.

BTW, just in case the server should go down and you get a different IP address, you should look at www.no-ip.com.

Do you have the Windows firewall on the server enabled? (It's enabled by default in XP.) If so, you have to punch a hole in that too - or just turn it off, since the D-Link is a firewall.

Tests:

From a computer in the domain, connect to the internal address of the server with IE. Does that work? (Do you get to IIS?)

From a computer outside the domain connect to the public IP address of the router (not the 192.) with IE. What do you get? Timeout? Unable to connect? The router login?