One of my PD problems is that when my tremor is bad moving the mouse accurately is difficult.
There's a neat, free piece of software that can reduce the problem. It can be downloaded from:
http://www.steadymouse.com/
I'm always relectant to download software off the web in case it contains viruses. However, I've had no problems with steadymouse.
It's written by a guy called Ben Gottemoller, to whom goes my thanks.
John