I purchased this keyboard after having problems with carpal tunnel syndrome. I practically live on my computer, whether as a freelance writer, researcher, or just for fun. So without even researching it, I believe that I ended up with, possibly, the best ergonomic keyboard on the market. It has more features than I will ever understand or use, but the most important thing to me, is the improvement that I have felt in my wrist discomfort.
It features a split keyboard design (which feels a bit strange at first) but after a little practice, it quickly begins to feel normal. It has a wave like appearance, and the place where your palms and wrists rest, is covered in a soft, padded material that is really comfortable. It also has a removable riser which enables the keyboard to be angled away from the typist, for better wrist support. But if you decide it's not for you, it can be taken off with no problem.
The keyboard is very quiet, with an easy touch. It has a zoom slider in the middle, for magnification of the text, and more bells and whistles than this girl could ever explain. It even has a calculator button which comes in quite handy. The Microsoft Natural Ergonomic Keyboard 4000 does use a wire, and it connects with a USB, but has a PS2 converter included. (Yes, that part I got out of the instructions. I'm a little out of my comfort zone here.) It also features many hot keys and multimedia keys. It is compatible with Windows Vista, Windows XP, and Windows 2000 SP4 or higher.
The best thing I can tell you, is that it really helped with the discomfort that I was having with my wrists, and I will never go back to a traditional keyboard again. I love it!!!