I have used simplelan with just serin on a 28X1 for 6months+ now, so for simple on/off pins you dont need the hserin.
18X and 14-m didnt work though.
Modtronix do some SBC65EC boards too, they contain everything needed to change some pins, but a bit pricey, and can already be coded in C, so the picaxe idea is a bit lost.