Luciano,
The handyboard serial interface board a seperate power supply input from the microcontroller. The only connections to the PC are TX, Rx, and ground.
I forgot to mention that the interface board green ser. led does illuminate briefly when windows is booting, but extinguishes when the 'windows splash' displays. Since my first post, I've also checked this on a Win98se notebook with the same result.

Cris