Microchip has a ethernet interface chip (ENC28J60). It'll do you right, but it'll take a bit of gumption to get it working.
Use the Pictail so you don't have to spin a custom board.
http://www.microchip.com/stellent/id...ame =en027750
Alternatively, put a gumstix in there. It'll put you back a little bit more in terms of $$, AND you'll have to learn a new environment. However, it also has a bit more kick to it.
http://gumstix.com/
Good luck, and let us know how it turns out!