Jack's link and reply just tell you that what your suggesting isn't going to happen. If you want to use your second Router/AP combo to extend your WLAN then you'll be running a cat5 run to it. If you want to extend wirelessly you really only have two options. Buy an AP (not AP/Router combo), stick it in "client mode" then use a crossover cable to another AP to do the broadcasting, or buy an AP that can be setup as a repeater. The problem with the second solution is that repeating is not Wi-Fi certified so if you buy one of the AP's that has that functionality, Linksys or D-Link gear for example, there is not guarantee it will associate and repeat to your existing parent AP. Since your main AP is a linksys then if you bought a Linksys repeater it would most likely work fine. Your only going to use one of the AP/Routers you have currently in either of the above solutions. If you want to use both of them then you'll be running cable to the second.
Edit: Or buying a third device to associate the first AP as a workgroup bridge or "client mode" then using a X-over to the LAN side of your second AP/Routers integrated switch..