How can I turn off my Time Capsule's wireless router? I have a useful wireless network, and then my Time Capsule's wireless network, which overpowers the other network when the computer is next to it. I don't know if it's misconfigured, but the Time Capsule's wireless network lets me do Time Machine backups and nothing else.

Is there a way to turn off the Time Capsule saying "I am the network" or configure my MacBook Pro (Lion) to ignore the router's network unless instructed to? Or how can I configure the Time Capsule, which is plugged in to a working wired network, to be a better router and forward traffic appropriately?
Yes, using the Airport Utility you can turn off the router and WiFi functionality independently of each other.

Under the Wireless tab - Network Mode: select Off
Under the Network tab - Router Mode: select Off

At this point you can connect the Time Capsule to the wired network using the ports with a horizontal icon &lt;-> or even use it to receive the internet and connect your router to the ethernet ports. Bridge mode disables firewall, port forwarding, DHCP and DNS and makes it simply a network peer.