Building new home network need some help

I am currently running a ubee charter cable modem on 100mb service to a netgear wnr3500 v1 router to a 5 port netgear gs605 v3 giga switch the biggest problem i am having is i have 3x xbox360 and 2x ps3 and i have a hard time getting the 360s all on live at once so what i did so far was the following:

I purchased a linksys ea6500 router and a cisco SG100d-08 8 port giga switch. What i would like to do is the following:

Run the ea6500 to the cable modem as the main router/firewall and connect the wnr3500 to a lan port of the ea6500 and the wan port of the wnr3500 disable the dhcp ect on the wnr3500 and use it mainly as a dmz passthru of the ea6500 by assigning a ip from the ea6500 and that ip putting in dmz to bypass the firewall of all things connected to the wnr3500.

is this the best method for doing what i want as i need all the 360 and ps3 to see the other pcs and network from the ea6500.

if anyone has a better solution or if this would work let me know i am planing to start the tear down and rebuild tomorrow.

in all between connected stuff in house is about 20 devices over wifi and lan.

i did read somthing also about giving the wnr3500 router a diffrent ip like 192.168.2.1 and have the main on 192.168.1.1 with same sub nets and could use the wnr3500 as a dhcp yet and still set the ea6500 to dmz from the wnr3500 ip and be able to pass stuff thru also but not sure if i read that all right.

I'm trying to figure out what you're actually trying to do from what you're describing.

Are you trying to get all 3 xboxes in the DMZ? If so, you're not going to. Only 1 computer can have a given port open to the outside world. The router has a "link" that tells it what to do with a packet coming in for port X - it goes to computer Y. You can't have some requests for port X going to computer Y and some to computer Z - there's no way to tell which goes to what. If you want all 3 xboxes to be open to the internet on the same port, you need 3 connections to your provider.