virtualbox.org

I've been trying to switch to VirtualBox from VMWare, but one sticking point is I've been having a hard time figuring out how to set up multiple guests on the outside network.

The first host goes easily enough- new interface, bridge to the physical adapter, done. The trick is that to do it again for a concurrent machine the physical adapter is no longer available for bridging.

Is there a good way to do this short of running a router vm?

You can attach several interfaces to the same bridge. You can't create more bridges on Windows though, just one is the maximum.