Also, there are some nice fanless Mini-ITX boards out there with dual gigabit, which is all you need (plus a case for a board and a switch, of course). M350 en

Also, there are some nice fanless Mini-ITX boards out there with dual gigabit, which is all you need (plus a case for a board and a switch, of course). M350 enclosure is popular and cheap. It goes without saying such box will smoke anything you can buy of-the-shelf. Hell, even the anemic ALIX Geode gave a nice boost to my home network over the crappy Linksys I had previously (things are now snappy and 100% stable).