There's plenty of good suggestions in here, so I'll just add a small pointer: SmartBoard keyboards from DataDesk Technologies. "Oh, go buy an ergonomic keyboard!" sounds like trivial advice. A few years ago, I had wrist pain--not as bad as yours, but plenty sufficient to scare me. I bought this keyboard, and it vanished. They are also durable: I've had one for 5-7 years, I use it 8-10 hours a day every day and it's just starting to lose some keycaps.

The only problem is that they are almost impossible to find.