gaming router

Good day folks,
i play online games, i have 2 xbox 360 consoles and a network setup at home. since the purchase of my second console, i get some 'laggin' issues from time to time...each minute i miss a beat which is pretty anoying. i have cable modem, my dowload after test are 6785kb/s and upload at 700kb/s which apparently is way sufficient. i have an old router D-Ling DI-524 not wireless and i'm wondering if this is the problem. i know there are gaming routers at 200$ but if i can pick up one at 75$ because the other one might be faulty, i would prefer. Before i had two consoles, if another member were browsing on the web while console was networking on a server, we'd get lagging issues also. if you can recommend another router if you think this might be the problem or other advise...
i did upgrade firmware but no change. pc isn't even open so it's not taking any bandwith. E6600 @ 3.0 3 gig of ddr2 800mhz. raptor...bla bla bla. i even removed firewall to see...

thx