Long version
I have the internet feed to my house coming into my office by TC cable modem, which is way down the back of my house. Right now it plugs into a Linksys WRT-54GL running DD-WRT which provides wireless service to the house, and I plug a cable into my main PC. In the body of the house there are two iPods, an iPhone, and two laptops. They only really talk to the internet, not each other. Signal strength is low but works fine now I increased the router transmit power. The Linksys is a B/G router, not N, but given it's a 15Mbps internet connection B/G is plenty.

I recently added a TV and PS3 to my lounge, and both need a network connection to connect to other PCs and to the internet. My latest plan is to run an ethernet cable from the main router under the house to the lounge and put a switch/WAP in there. I got a D-Link DIR-615, which is B/G/N, and a 25m ethernet cable. The extra WAP will just give better signal strength, reduce device battery usage, etc. I figured for an extra $80 over a cheap switch I might as well have the extra wap, which will help if I do VOIP.

One router will have to act as the main router, using the static IP of my internet, doing DNS and DHCP, etc, and acting as a switch. The other will just be a switch/WAP, and won't really provide any services. I'm not sure which router to use as main.

My questions:
 - Which configuration would be best, and why?
 - Is there anything I need to do with two routers on the network? Obviously I have to make one the main, give it my static IP, and on the other just make it a repeater and disable unneeded services like DHCP and probably DNS. I'll probably have to check they're on different channels too.


Short version
Given I have a D-Link DIR-615 Wireless N router and a Linksys WRT54-GL B/G router which should act as the main router/switch at the back of the property and which should act as a switch/WAP in the main body of the house?