Lost internet access on other Win XP desktop after wireless router install

I have limited experience with this. Just hooked up a Netgear WGR614 wireless router on our DSL system to add another computer. The install went fine and my Windows (Windows XP Home SP-2) desktop internet connection is fine along with that of the other computer that was added in via wireless. Both machines are fairly new Gateways. Went to use another desktop on my computer (one connected via DSL modem) and it is unable to connect to the internet now. As I mentioned, the installation went fine and I haven’t gone in and reset any of the original settings. Any suggestions? Many thanks.