Yep, doing a more ergonomic set up on my desk here made my life better too. I had some write/forearm pains too and went with a vertical mouse, and that did the trick. I couldn't get used to a trackball for some reason. Also went with an ergonomic keyboard and that also helps. I don't do any gaming on here, just work stuff.
I have heard good things about Vertial Mice but I've fallen in love with Trackballs once I embraced my first one, I don't know if I can appreciate normal mice since.
