I bought this for my cross country trip. It uses the same 4-position DIP switch to set the FM frequency, but takes power from a laptop's USB port, and also appears as a pair of USB speakers to Windows. No driver to load at all. Just plug 'em in, and choose the new set of speakers in Winamp's output options. Was very easy to setup.
Worst POS idea ever. Could have been due to the close proximity between the laptop and the FM transmitter, but even separated by 3 or 4 feet, the sound had a continuous high pitched whine. Made no difference if the laptop was powered off batteries, wall power, or the native 12v adapter I bought for the trip. The sound was terrible. The PAC Audio kit was still a month or more away, and I wanted to lay the foundation for a carpc, so it forced my hand to buy the tv kit with the 3 inputs and hardwired FM modulator. No whine whatsoever. I'm sure the range is limited compared to the PAC, but I'm not that much of an audiophile, and it still sounds much better than the LineX box I tried. I even tried to beam the sound across a moderate-sized hotel room in Manhattan so I could go to sleep to and wake up to my music. No way.
If I heard that whining sound for about 17 days in the car, I would've gone completely berserk.