Just a couple of other things that were mentioned in the seminar last week at Cabin Fever...don't know if this is help or hindrance...
It's more difficult to clean the laptop keyboard or keep swarf out of it. You can pick up cheap keyboards for a desktop pretty cheap. If necessary, it's also easier to pop the keys for better cleaning. If you still go by way of laptop, you can use an external keyboard and keep the laptop covered.
You might consider getting a cheap, no frills, desktop box. Or get a used one and put a new clean hard drive in it or get someone to take all the 'junk' applications off. Just use it for controlling the machines. Nothing else. Because of the task switching between applications and the operating system, the timing to the port can be 'interrupted'. This might be less of an issue with faster processors. If you do want to use the box for other applications, I wouldn't run them while running the machines.
I would avoid the USB too. At least any kind of converter from/to USB. Keyboard/mouse is probably okay. I develop communication systems using USB. I'd like to find the fella who developed that specification and knock some sense in him.
