Portforward is out of date when it comes to the new WRT54G firmware. Here's an updated walkthrough for Firware v3 With windows XP sp2. (By the way, I suggest updating your router firmware, even though Linksys doesn't recommend it unless you're having problems. I just love new features
First: Set up your router and internet connection as usual. If you're having problems with this step, you need to stop and go read your router's guide.
Second: Go to Start->Run and type cmd. this will bring up the command prompt console.
Third: Type "ipconfig/all" in the command prompt, and hit enter. This is the info you'll need to set up a static IP address. If you don't see any DNS servers listed, you'll just need to look for them on your router page. Again, if you're having troubles doing something like this, getting BT to work better should be somewhat of a secondary concern. Click on the Status link on the top bar on the router page, and then scroll down to the DNS addresses. Write them down and move on to the next step.
Fourth: Open up your router page (if it isn't already). On your router's setup page under the Basic Setup screen look for the section called Internet Setup. From here you need to
a) Change the connection type to a static IP, then
b) scroll down and find the Network AddressServer Settings
under the network settings heading. Click the disable button beside DHCP.
c) Scroll down and click save, and then continue.
Fifth: Now you should be back to the Setup-Basic Setup page, and your changes should have taken effect. At this point you want to get to the properties window for your connection. There are several ways to do this, so if you're one of the people who know them, feel special. For those of you who are still getting over the fact that a mouse isn't just a furry rodent,
a)click on Start->Control Panel->Network Connections. Then
b)click on either Local Area Connection (if you’re the router) or Wireless Network Connection (if you're the wireless).
c)Click on the Properties button on the screen that comes up. This will bring up another screen. Here
d) click on Internet Protocol (TCP/IP) and click on the Properties button.
e)Click the buttons for "Use the following IP address" and "Use the following DNS server addresses" then enter the info from the cmd window into the appropriate places.
f)I don't know how much of a difference having a third DNS address makes, but if you want it for whatever reason, after you've entered in the other two DNS addresses click the Advanced button, then the DNS tab, and click the add button. Enter your address, and click ok/apply on all the windows that've come up since step d). When you get to the window that has the properties for your connection, click Close -not- Cancel. It'll take a second for all the settings to take effect, so sit tight. Eventually the window will close, and you're done. Cheers!