That router has a speed of 100 Mb/s wired, and 54 Mb/s wireless. The only thing faster is Gigabit.
You can upgrade to what I have, a D-link DIR-655, Gigabit/wireless N. My machines are all Gigabit and wireless N. But then you'll have to upgrade all your other stuff to Gigabit and N.
Keep what you have.
First of all I have the Linksys wrt54gs router, and I have Verizon's DSL it's 3mbps and I am upgrading to symmetrical fiber 12mbps. The things i have connected to the router is a ps3 on wireless, 2 laptops, 2 computers. And if this might help I do play games online and i download alot and watch shows online aswell.