I'm also a cranky stubborn old man. And lazy. If it was me I would use my car odometer for mileage. That way I don't have to screw around with a computer and GPS.
Being lazy and cheap I would head for the nearset Staples and pick up a small notebook specifically designed to make it as simple as falling off a log to keep track of time and mileage.
If I was really opposed to pen and paper, which never has to be recharged, I would use a PDA for this sort of thing.
Using a computer for tracking time and mileage is a real pain, compared to alternatives like paper or PDA which make it almost trivially easy.
The startup time alone is a killer. Then you need to wait for some application to launch. If you're going to try to include your nav software in the mix somehow, you need to wait for the GPS to get a location fix.
And you still need to figure out some way to identify when the business portion of a trip started and when it ended.
If you really want to be totally automated find a suitable application for PDAs and get a PDA. You can get applications that are designed specifically for such tracking, for consultants, lawyers, real estate folks and other people who need to track their expenses, including time, mileage, meals, accomodations, whatever. The good ones are designed to sync with something on the computer.
If Quicken is your central tracking tool, I suggest you look at Pocket Quicken. You can get it for Palm OS and Pocket PC.
Here's a review.
Pocket Quicken Review - Pocket Quicken Personal Finance Software for Palm, Pocket PC and Windows Mobile
Or you can just run Quicken on your netbook. Make entries from your watch and odometer as appropriate. Anything you are doing now on your laptop you can do on a netbook. My netbook actually has the same speed processor, the same RAM and same hard drive space as my laptop.
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