I would try and stay away from plipbox. Have read elsewhere they can be problematic. Plus you need to power it externally as well, so more cables flapping around at the back to contend with.
I have many plip box,they are slow, 32K/s on the good side if memory serves. I have never had any trouble with them,but i would go for the pcmcia adapter and a wired or wireless card..
vampire accelerator has ethernet but not a cheap solution.
