Is the problem in your wrist? Both wrists? In your fingers? All fingers? In your arm ? Both arms? In your neck?!
The equipment may not be able to help you, and unless you can determine what is causing the actual problem, new equipment may do more harm than good!
First thing is, go see a Doctor.
Listen to what he/she says, and then determine whether changing your keyboard (or even mouse) is really going to help. I tried an ergonimic keyboard for a short period asI had some major wrist ache, turns out I was just watching too much porn.. Nah, seriously, it was due to how I use my mouse. For me, the solution was to use a wrist rest when using mouse.