If all you want is to use the router as a switch then bridge mode is completely unnecessary.
You just need to make sure the second router is on its own static IP address, or DHCP client if capable, or stick it on a completely different IP address range entirely. Basically, we are ignoring all the router part of it so we don't actually need it visible on the network at all so make sure DHCP server is disabled on it too.
Leave the WAN port empty and plug everything into the LAN ports, including the cable linking to your main router. This way the second router WILL just act as a switch.
Most good routers have a hardware switch in the router, so it will behave exactly the same as a dedicated switch. Two of the three gigabit switches on my network are actually routers and achieve gigabit speeds without issues.
Edited by alexatkin (Tue 20-Aug-13 22:36:41)