[masraum]

Yes, I second getting a good Trackball. I've always used Logitech pointing devices (first mice, but for many years now only trackballs). I used to get a sore wrist until I switched to trackballs.
http://www.logitech.com/index.cfm/mice_pointers/trackballs/&cl=us,en
I use one of these at home

and one of these at work


And I have one of these on another computer at work.


A wrist rest for the mouse and possibly keyboard would also help. I actually have an old ergonomic keyboard that tilts away from you and found that it is much better than most of the rest that tilt toward you. I think I saw a Microsoft version the other day that did the same.

I've always liked the microsoft keyboards.
http://www.microsoft.com/hardware/mouseandkeyboard/productdetails.aspx?pid=043



I used to use keyboards like those above, and really liked them, but I use something much different these days.
I would happily recommend these, but probably only for the really geeky that puts in a lot of keyboard time. They're a bit pricey when you can get most keyboards for $10-60.
http://www.kinesis-ergo.com/contoured_usb.htm


And here it is compared to a regular ergo keyboard.