multihoming question

I'm looking at getting a second internet connection and I was wondering about connecting it to our Mac Pro server's second ethernet in a setup I think known as multihoming. The Mac would use the connections in the order specified in network preferences, yes? I seem to remember though that setting a different router in the second connection doesn't work, and it should be the same as the first. Is that correct? Or can Snow Leopard cope with that? For example if you set a particular service to bind to the IP on the second ethernet, will it just send traffic for that service that needs to be routed to the second router without any problem? That's assuming the second router is on the same subnet and has DHCP disabled.

thanks