The Microsoft Natural Ergo Keyboard 4000 is a popular low cost ergonomic keyboard.

The goal is to have each wrist on top of the keyboard without twisting the wrist. Everyone has a slightly different distance between each hand, but this keyboard has a fixed width and angle between both sides. One size fits all.

I prefer this Kinesis Freestyle solo Keyboard instead.

American Journal of Roentgenology has a good article covering computer ergonomics and Carpal Tunnel Syndrom.  The diagrams show exactly what type of situations you should avoid.

The Kinesis Freestyle solo is a low cost split ergonomic keyboard.  It allows you to detach each side and position it independently.

The goal is to have each wrist on top of the keyboard without twisting the wrist.  Everyone has a slightly different distance between each hand, so this allow independent positioning.

Office Master makes the Discovery DB96 computer chair that I use.  It has a unique pear shaped back shape that forces me to sit correctly.  It is also fully adjustable.  Check it out at your local store.

Office Ergo has some tips for selecting computer seating. Key elements to look for in a new chair:

1) Adjustable Seat Height

2) Seat depth Adjustability

3) Backrest height and angle Adjustability

4) Chair Recline

5) Seat pan angle Adjustability

6) Lumbar support and Adjustability

I have had problems with arm rests in the past.  Typing with arms on an arm rest lead to problems.  I ditched my arms.

You may need to goto a computer chair or ergonomics speciality store and not an office product super store to find your optimal chair.  Try a chair before you buy.