Home routers are getting pretty smart, you can load OpenWrt Linux on these.

I'm looking at the D-Link DIR-825, it had fastest CPU on the list below (680 MHz), plus 5 ethernet ports, two internal wireless routers (2.4 GHz std and 5 Ghz for HD video / gaming) and USB for storage and/or printer sharing ($130 at Fry's). Also the OpenWrt support looks better for this router than the one I was originally considering, a LinkSys. The RouterStation routers were also at 680 MHz but no wireless and not really a name brand, I think.

I've been looking for a while for a small home file server and I think this may be it.

OpenWrt's list of Linux-loadable routers:

http://wiki.openwrt.org/toh/start