Internet Lag Patches

Recently I've started to experience about a 30 second lag every 5 minutes or so when I'm surfing the web. I'll be moving along fine then wham, I have to wait forever for the page to load. Refreshing does not help, it's still waiting to load. I'm also experiencing horrible lag issues with my online game. I don't have this lag with anything that is not internet related. The problem began at a period when a few things happened so it's been very hard to pinpoint. We had a power outage, when it came back up there was an issue with the cable internet. In the process of diagnosing things with the cable company the router was found to be bad. I replaced the modem. The old modem was a Lynksys, not sure of the model, and the new one is a US Robotics 8004. The was also a big patch of my online game at the same time. I don't believe this is the issue because it's happening outside of the game too. I have also replaced the cable modem with a Motorola SB5120 to no avail. Both the cable company and the router manufacturer have been less than helpful. The problem exists on both PCs I have running thru the router. I have run anti-virus software and both Adware and Spybot, with their most current updates. I have defragged, run ScanDisk and System Clean Up. Both systems are running on Windows 98 SE. I have not removed the router from the computers to check it without router due to the degree of inconvienence and irritation in doing so. If it didn't happen without the router, what in the router could be causing it? And if it did happen without the router, what with the cable system would make it suddenly start doing this? Was wondering if anyone could offer any ideas please? Thank you very much.