Mounting it on the dash like that can transmit vibrations into the computer from the dash. If you use that type, I'd make use of some form of shock absorbtion or padding.
Here is one site I googled:
LINKAnother option is to look on Police Supply sites. Alot of agencies are using laptops or mobile PCs in thier units. My agency recently went to the Motorola MW520. I bought one off of ebay for $250... it's going into my ZJ.
Since the Motorola units are mobile, they have specific brakets. Police supply places such as GALLS carry mounts for laptops. They are also adjustable.
Right now, I have no laptop mount. I have an Averatec laptop with the 12.1" screen and MS Streets 2005 with the USB GPS module. Works great.