Alternative mouse?

I am starting to feel uncomfortable (one step short of "pain") in my
right wrist, and I'm convinced it's because of my mouse.  It's just a
regular mouse, used on maybe 90% of the computers in the world. 
Whenever I'm finished moving the mouse and pick up my right hand, my
first response is to roll my wrist until my palm is facing upward?

Does anyone here have any experience with an alternative mouse? The
ones that  I'm looking at include:

Wow-pen Eco

Wow-pen Joy (just out)

Evoluent Vertical Mouse

Microsoft Natural mouse

Suggestions?

Steven