On the mother board of a PC you have two PS2 connections, one for the mouse and the other for the keyboard. If you plug things in backwards they just don't work and you have to reverse them. They have started color coding all the plugs on motherboards pretending this is going to solve hook up problems. Now that you mentioon it, if there's only one ps2 plug on a unit it doesn't matter what you plug into it. I have no idea why when there are two you need to use the right one for the right accessory. It won't hurt if you plug in the wrong thing on a PC mother board in this case, it just won't work and you just shut down, pull out the plugs reverse them and reboot. Now I don't know how this is going to effect ps2 to usb adaptors. My guess is they will say if they are use specific and you'll just have to use the trial and error method to get the right things plugged into the right plugs.
When there is just one ps2 socket on a notebook, my understanding is you can use either a keyboard or a mouse in it. Perhaps you needed a driver to make the keyboard work there that didn't work, um was that Isaac who had trouble there?...well, whoever said that.
