I've been down this road...pun intended. With all the available mp3 cd players and flash players available today, using a computer just isn't worth the trouble.
For spreadsheets, your problem is gonna be daylight readability. Doesn't matter what's under the hood if you can't read the screen. Look into laptops for police cars...but take two wallets with you.
If you plan to do all this while on the move, you'll also need wrongful death insurance for the prople you kill with your car. mike