If you don't care about the electricity costs, I would assume a PC router would be the best solution. Just get 2 gigabit Ethernet ports and plug one as wan and the other into a gigabit switch.
I don't know how to do the software side of this though, and would like guidance as to whether this would be possible in just Windows without having to resorting to *nix?
I don't know how to do the software side of this though, and would like guidance as to whether this would be possible in just Windows without having to resorting to *nix?