Firewall would be my first guess
My Belkin router is 192.168.0.1
Is there a light on the front which has a number on it? On most routers if the light is not on then the connection has not been made.
If you are sure that it is conencted then maybe the TCP/IP drivers are corrupt. Delete the drivers in control panel> Hardware then restart the machine and windows xp will reinstall them automatically.
TIO