Needless Design Changes
Microsoft hasn't minded "messing with" the layout of the Home-key block. On the Multimedia, the Delete button was huge. On the Elite, it is shrunken, but the keyboard now puts the Insert button down in the group. On the Multimedia, it was a third function of the PrtScn/SysReq key! The F-Lock button, which toggles the top row between F1, F2, etc. and the special functions, is disabled by default on this keyboard. So if you're accustomed to using the function buttons in your favorite application, this will annoy you until you learn to press the F-lock button each time you start your computer.
Microsoft Natural Ergonomic 4000 Keyboard
My current keyboard is the "Natural Ergonomic 4000." Actually, it's my second one. The first died right before a business trip in December 2007. This keyboard is quieter than the previous models and has a different feel in the key return. I first thought that this would be an issue, but I got used to it. The left, right, and up and down buttons are back in the inverted-tee, and Microsoft has messed with the Home-key block again. They are now in a horizontal row with Insert and Delete on the nearer end. The wrist guard now has a soft, leather like texture that is quite comfortable. Thankfully, the keyboard now remembers the status of the F-lock button and it persists after restarts.
Natural Ergonomic 4000 Keyboard

Features of the Ergonomic 4000
The 4000 has five programmable buttons along the top row that can be assigned to "Favorites." A Favorite can be the path to a program, a Web page, or a file. Strangely, they cannot be assigned to folders. Below is a screen shot of the control panel.
Rounding out the other top row buttons are Home, Search, Mail, Mute, Volume minus and positive, Play/Pause, and Calculator.
The keyboard also has a zoom slider in the space between the split. It has the same effect (in compatible programs like Firefox, Word, and WordPad) as pressing Ctrl + scroll with the mouse.
One negative note about the 4000 is that the key labels are poorly printed. The S, D, F, K, and L keys have all rubbed smooth already, and this keyboard is only a few months old.
The figures below show the Zoom settings and Favorites settings in the keyboard control panel.
Settings for the Ergonomic 4000


Summary
So are the Dvorak keyboard layout and the Microsoft Ergonomic split keyboards a match made in heaven? They are for me. Thanks to both I can type for long hours without tiring and feeling pain and that helps me to stay productive. And since all modern operating systems offer the Dvorak layout, it costs you nothing to try it. For ergonomic computer use in general, the most important thing in avoiding repetitive stress compression injuries and hand, wrist, or shoulder fatigue is to maintain good posture. This means that your seat should be high enough, or your keyboard low enough, to maintain a 90-degree angle of your elbows with your wrists in a neutral postion when placed on the keyboard, your spine against the back of the chair, your feet flat on the ground, and your shoulders relaxed. It also helps to keep your mouse as close to the keyboard as possible.
Update
Sept. 25, 2008. My second Microsoft Ergonomic 4000 keyboard has failed, and I'm typing this on an old Natural Elite. The left Shift button stopped working first, and then the entire extreme left side of the keyboard stopped responding. This is consistent with the failure of the previous keyboard. My conclusion is that the Ergonomic 4000 is not up to heavy use. I won't be buying another one. (I'm going to try a find a used Natural Multimedia on eBay.)
Related Reading
Another Bright Hub Review
Microsoft Natural Ergonimic Keyboard 4000 - The Microsoft Natural Ergonomic 4000 is currently Microsoft's best-selling keyboard. Having used the keyboard for one year, I will provide you with a true review of all aspects of the MS Ergonomic 4000.
Links
Here are a couple of informative websites about the Dvorak layout.
1. Introducing the Dvorak Keyboard
This website site by Marcus Brooks is an excellent starting-off point for All Things Dvorak and was the source for much of the information in this article.
2. WWW.dvorak-keyboards.com
Malcolm Greenway manages this website. It is another good starting point, and on this page, you can download a full-sized graphic of a Dvorak layout that you can print out and experiment with. On that page, note how the F, D, and B, and the Y, I, and X keys are extensions for the seventh and fourth fingers. This is exactly how Microsoft has divided the keyboard in all the ergonomic models, and that's why they work very well with the Dvorak layout.