So this might be interesting for some of you using the laptop solution like I am. I've hacked the power button my laptop so that there is a dongle which comes off of it. I use this box:
http://lh4.ggpht.com/_jABUXREarfE/SkTmwGkDofI/AAAAAAAACro/uy4LLholbtA/s512/dsc00502.jpg
(Red wire leaving the box is connected to relay on timer board, black wire is connected to DC to DC converter)
To provide both DC to DC power conversion (the large silver thing labeled 19v 16v on the top). As well as a one-shot, 1 second relay which triggers the laptop when the car is powered. The laptop is then configured to stay running until it reaches 70% battery life then it shuts down. This allows me to continuously charge the thing when the car is on, as well as have it run for quiet a while so I can say, sync files via wifi to it when I get home, or not have to wait for it to boot back up again if I'm making lots of stops. Once the laptop does shutdown, it only goes into standby mode, which it can sit in for literally weeks at a time without a problem.
Also, this box happens to fit perfectly under the radio, so I have the dsub video, USB, power, and power on wires running under the passenger seat where the laptop sits, so the install is mostly stealth and easy removable.