Well, I can type 100+ words a minute when I'm just typing off the top of my head (typing from a book makes it a bit slower). I don't usually look at either the screen or the keyboard exclusively, but I tend to look more at the keyboard than the screen, even though my fingers are going way too fast for me to see if I made a mistake while look at the keyboard. I just type and I know when I make a mistake. I was a pretty competent typer when I started playing guitar like 4 years ago (60+ w.p.m. back then), and I've noticed that on the physical coordination side, things come a lot easier to me than most people. But typing and guitar are two different beasts... there are different motions involved, but you're muscles are already strong from typing. It just takes a minute for the brain to learn where to move - the hands already have the ability to do it.

Try this one for a coordination exercise... looks pretty cool - set your wrist and fingertips down. Lift your index and ring finger simultaneously. Set them down. Lift your thumb, middle finger, and pinky simultaneously. Set them down. Repeat process.