Can't Open Ethernet Wireless Router On XP But Works With Mac

Our home school's having trouble attaching a wireless router to my XP PC's ethernet port.Our donated vintage Macs and XP machines are tied to the internet via a cable box's wireless router. Works just fine. Now I wish to boost the signal to a building beyond the local area by attaching a wireless router to a Dell 260 running XP. This router's IP is 192.168.11.1 (ON) and 192.168.11.100 (OFF), and I've spent hours with the Connection Wizard thing on XP trying to create a ethernet path to the router but I can't find a configuration that states an ethernet path or channel. The modem lights normally and other machines can pick up and connect with its signal but there's no real transmission, the receiver machines getting:Firefox can't find the server at [URL].Check the address for typing errors such as [URL]instead of [URL] If you are unable to load any pages, check your computer's network connection.If your computer or network is protected by a firewall or proxy, make sure that Firefox is permitted to access the Web.Ironically, the router works just great on the Macs, which has both Airport on to receive signals from a cable TV wireless router and also has its shared Ethernet connection on, and the ethernet side requires no IP configuration like it seems you must on the XP's internet connection page. The router in question just plugs in the Mac and transmits just fine. I would use the Mac for this purpose but I really wish to use the Dell.The Dell's current network configuration after many trials:

Wireless Connection 3
LAN / High Speed Internet
Connected, Firewalled
802.11n USB Wireless LAN Card
IP 169.18.2.7

[code]....

Oddly, the Mac's Network panel states: "The cable for built-in ethernet is connected, but your computer does not have an IP address and cannot connect the internet." Yet it does!