Quote Originally Posted by MisterEd View Post

Why would he be getting a 172.xx address off the LAN side of his WRT router to his (XP) computer. Unless he made changes the "normal" IP generated on the lan side would be in the private 192.168.x.xxx range. I've never seen a router (out of the box) generate a public IP on the LAN.
172.16.0.0 - 172.31.0.0 are class B private networks. 192.168.x.x is class C and 10.0.0.0 is the Class A. All three are private subnets and are not routable on the internet.

Most of the routers are set to give a subnet in 192.168.x.x. I think the user must have changed it to the class B private address.