The Dvorak keyboard layout
Have a look at your keyboard. Is it a so-called QWERTY keyboard? (Or QWERTZ or AZERTY) You're not being nice for your hands if it is. Dvorak is much more comfortable.
Dvorak Keyboard Layout
~ ! @ # $ % ^ & * ( ) { } ____
` 1 2 3 4 5 6 7 8 9 0 [ ] BS
___ " < > ? + |
Tab ' , . P Y F G C R L / = \
____ _ _____
Caps A O E U I D H T N S - Enter
_____ : _______
Shift ; Q J K X B M W V Z Shift
I'm not going to explain why QWERTY is bad and why dvorak is much better. Shiar has already written a great page about dvorak, so I'll just refer to his dvorak page instead.
Learning Dvorak
If you want to learn Dvorak, my advice is to leave your keyboard in QWERTY order and learn the new lay-out without looking at the keys. I made an online typing tutor that will help you learn Dvorak. It shows the keyboard on screen, so you do not have to re-arrange the key caps.
My experience
I started learning Dvorak in July 2002. The first week was the most annoying. At that time, I hadn't created my learning system that is on dvorak.nl, and I was foolish enough to re-arrange my keys. Looking at the keys slowed my learning process down. In this week, I went from baby-speed in the first few days to reasonable speed (200 CPM) near the end of the week. After two months, I regained my old QWERTY speed.
Whenever I need to work with someone else's computer, I usually ask if it is okay if I temporarily adjust the keyboard lay-out. In Linux virtual consoles, it is a matter of typing loadkeys dvorak to get Dvorak (root access is usually not required) and loadkeys us to get back. In X, setxkbmap does something similar. Windows and KDE let you configure multiple lay-outs that you can activate using a key combination or a system tray icon. Most people are comfortable with changing their configuration, as long as I restore it afterwards :).
In the rare occasions that I really have to type QWERTY, I just look at the keyboard. I still type QWERTY at normal speed, but I need to look at the keys to know where the keys are.