routers

we have a new router installed with its own ip address of course and still have the old one in place also for a few more days. when i log onto the network my pc points toward the new router to access the internet and the “speed test” shows a 500 range (partial T-1) connection. But when i access one of the sites under My Favorites…..it reverts back to the old router which is isdn….Why and How do i change this for each win98 workstation?