Ergonomic Mouse

I work a lot in front of a computer with 3d graphics.

When I have read a bit to an ergonomic mouse would be good and work with over time, I hear about somebody's experience with it?

I will of course keep my MX518 for gaming and sundry. But for work, I would like to have one there is little healthier and sit.

The mouse I am talking about,

http://www.verticalmouse.dk/billeder/vm3_sm.gif

http://www.verticalmouse.dk/billeder/in_hand_3.gif

Thank you!

I do not know how much track balls being used today. But I was very pleased with the Logitech I bought at the time. It requires some tilting but once it has come used to, I thought this is not a problem.

I had a little older model compared to this one:

http://www.logitech.com/repository/63/jpg/228.1.0.jpg

But they were organized in similar ways.