I'll cast another vote for XP Pro and the Dell D610 or D620. (We use D620s). The built-in legacy 9-pin serial port is absolutely, positively a 'must-have' in any service department-orientated laptop. And by "Legacy" lets be clear that I mean the serial port operates as either Com1/IRQ4 or COM2/IRQ3. We've seen instances where the USB serial port adapters sometimes work, but more often they don't, or behave erratically and are unreliable, and the tech is screwed. Your best-trained tech is no better than the tools they're given to work with. Don't hobble them with schlock equipment.