Better setup for gaming?

I'm currently running a Netgear WNDR3700 dual band router. There's 6 devices on the 2.4GHz channel, and 1 on the 5.0GHz. There's Computers B, D, N, Z, and L on the 2.4GHz band, along with my PS3. Lately the bandwith seems to be getting nerfed to my PS3 causing tremendous lag and horrible connection to online games. Would I be better off getting a second router to put as the primary and run Computer Z and the PS3 off of the primary, and a crossover ethernet cable to the second router for lowered bandwith to the computers that just need internet for the basic needs? Or would it be easier and offer better connection to run a CAT-6 cable from the router to the PS3 and hardwire it in? The only problem with running a CAT-6 is it would need to be run under the house (which isn't a problem) So I'd need to get an outdoor cable, that's 75 feet long. If I chose to run the cable inside, I'd have to follow the roof, and get another 30 feet of cable probably. Will running that much cable affect the performance for getting better upload speeds? The primary goal is to get the PS3 so it takes the majority of the load, and maximizes bandwith to it for optimum gaming performance.

Or is it possible to throttle the bandwidth each of the other computers on the channel get with my current router? So say 60% of the bandwidth goes right to my PS3 by setting the PS3's static IP as the the main usage for getting bandwidth? I'm aware this would slow down the internet to the other PCs, but it would also devote a certain amount to where it is most needed.