Actually, that's (somewhat) normal; I have a Linksys router/WAP/4-port switch, and all my PCs get IP addresses like 192.168.1.100. Those aren't real IP addresses; they were set aside for use on LANs. Part of the router's job is to be a DHCP server, which means give out IP addresses (like ^) to anyone set to be DHCP client (how it should be). You should be able to go into router settings and set DHCP range (or turn it off; then you'd have to assign internal static IPs), and the router should have the real IP address of your broadband modem (which you can find in it's config).
Check your router's manual for more help. Hope this helps, and congratulations; broadband's sweet.