PdaNet rocks for using your compatible cellphone (mine is a Treo Centro) to connect your carputer to the internet. Just start the program on your PDA, and the computer automatically detects and connects. Even more convenient, I have the hotsync button programmed to start PdaNet. The connection is not bad at all.
I'm thinking of installing a docking device for my PDA in the cupholder. That way, the screen is also easily seen while driving. Otherwise, I will just run the sync usb cable to the handbrake console. I don't have an armrest.