[InclinedPlane]

I have extremely RSI resistant hands and especially knuckles (due to a genetic quirk). I can type all day on a rectangular non-ergo keyboard with my wrists on the table, and in fact used to do data entry for 60+ hours a week doing just that, with nary an RSI worry. But using a mouse for, say, 12 hours straight or through a regular 40 hour work week would definitely cause me pain, in the shoulder, wrist, etc. Here is the solution:

Use.

A.

Trackball.

Period. Especially at work. It's vastly better ergodynamics. It has a little bit of a learning curve but it's not that bad. And for clicking and dragging windows around and whatnot, it's just fine. And it doesn't stop you from using a mouse if you need to use photoshop or play an FPS game or somesuch. I have a mouse and a trackball on my home computer. If for some reason you spend all day in photoshop then you should probably switch to using a stylus input tablet.

[hopeless]

Totally agree. I've been using a Logitech Trackman trackball for about 10years now. During the periods when I wasn't using it I'd get wrist.forearm pain and bursitis on the wrist (I have plates there from a car accident). Stretching is still important but the trackball is a major leap forward.

If you have to use a mouse, please don't use an Apple mouse. They are generally far too small and don't provide any support. I'm still amazed that a company which does great hardware aesthetics completely fails to understand ergonomics.