I was thinking of using a Jornada handeld 720 instead of the iPaq. It has both an CF slot and a PCMCIA slot so I plan to put a VGA/TV-Out CF card and a network PCMCIA card. It also has a keyboard which is more friendly in the car than the iPaq touchscreen. All could also be done with the iPaq but I would need to buy a two-slot PCMCIA jacket and then the two cards (and would be without a keyboard) -- ends up being more expensive since I can get a Jornada 720 from ebay for $400.

However, the idea of a wlan sounds very very appealing. I have no experience with wlans. What kind of device would convert the cabled ethernet in the empeg into a wireless that can talk to the wlan card on the CE device? Is that the device you power with the 12DCto5DC converter?

[edit]
Another thought is bluetooth. Both the Jornada and the iPaq have Bluetooth. Do you know of some device that can plug in the ethernet port of the Empeg and comunicate using Bluetooth transparently to the Empeg?