...and how would I do that? Or is every router different? I got a D-Link DI-604 if that helps at all. Thanks.

This will sound like im being a total dick..

But

Read the manual that came with it.. if you lost it, goto dlinks website and grab the online manual..

better you learn yourself and understand it so you can use that knowledge later, than one of us spell it out for you

Virtual Server
The device can be configured as a virtual server so that remote users accessing services such as Web or FTP services via the public (WAN) IP address can be automatically redirected to local servers in the LAN network. Depending on the requested service (TCP/UDP port number), the device redirects the external service request to the appropriate server within the LAN network. At the bottom of the screen, there are already defined well-known virtual services. To use them, click on the edit icon. You will only need to input the LAN IP address of the computer running the service and enable it.

Name - The name referencing the virtual service.
Private IP - The server computer in the LAN network that will be providing the virtual services.
Private Port - The port number of the service used by the Private IP computer.
Protocol Type - The protocol used for the virtual service.
Public Port - The port number on the WAN side that will be used to access the virtual service.
Schedule - The schedule of time when the virtual service will be enabled.

Example:
If you have a Web server that you wanted Internet users to access at all times, you would need to enable it. Web (HTTP) server is on LAN computer 192.168.0.25. HTTP uses port 80, TCP.

Name: Web Server
Private IP: 192.168.0.25
Protocol Type: TCP
Private Port: 80
Public Port: 80
Schedule: always

Special Applications
Some applications require multiple connections, such as Internet gaming, video conferencing, Internet telephony and others. These applications have difficulties working through NAT (Network Address Translation). If you need to run applications that require multiple connections, specify the port normally associated with an application in the "Trigger Port" field, select the protocol type as TCP (Transmission Control Protocol) or UDP (User Datagram Protocol), then enter the public ports associated with the trigger port to open them for inbound traffic. At the bottom of the screen, there are already defined well-known special applications. To use them, click on the edit icon and enable the service.

Name - This is the name referencing the special application.
Trigger Port - This is the port used to trigger the application. It can be either a single port or a range of ports.
Trigger Type - This is the protocol used to trigger the special application.
Public Port - This is the port number on the WAN side that will be used to access the application. You may define a single port or a range of ports. You can use a comma to add multiple ports or port ranges.
Public Type - This is the protocol used for the special application.

Dosen't the whole DMZ thing mean everything on my computer is exposed to the internet 100%?

yes. I wouldn't recommend using dmz.


ok lets look over what you need to do:

* forward UDP port 27960 on your router to your computer running q3.

* start q3 and either use the menu to start up a skirmish, making sure to have at least 2 slots open for you and him (check sv_maxclients in console), then put in your timelimit, and fraglimit and load up a map.
-or-
start q3, drop the console and type /sv_maxclients 2 then load up a map /map q3dm6. you will now be in the game by yourself (waiting for him).

* have him run q3 and connect to your wan ip by typing /connect {ip} in the console.

if he still cant connect, try connecting your computer to the internet without using the router to see if its a router problem. if that works then you havent set up your router forwarding correctly.

be afraid, be very afraid.

Wow you guys - I think I reached a whole new level of idiocy. I just went to http://www.ipchicken.com and it told me that my IP was XX.XX.XX.XX. Not 192.168.0.100, like I’ve been telling my friend. Apparently, XX.XX.XX.XX is the IP given to me by my ISP, and 192.168.0.100 is an internal network address given by the router. I felt really stupid after discovering this…

BUT...

I'm in an apartment with one other roommate. Both of our computers are hooked up through the same router. I went on my roommate’s computer and went to http://www.ipchicken.com, and it listed his current IP address as XX.XX.XX.XX as well. Shouldn’t this be completely wrong? Doesn’t each individual computer have their own IP address? Or do we share the same IP address because we go through the same router?

EDIT:
Also, is it required that you set the protocol type as UDP? My friend and me recently played each other online in ZSNES NetPlay, but we couldn't establish a full connection under UDP. Only under TCP.

Under UDP, it would say that it "found a client" every time he tried to connect to me, but it would never fully connect...