This pops up from time to time.
Some of us have a problem with the the conventional keyboard and mouse - and some of us have a very big problem!
I got all introspective about the number of typos I was making - and most of them seemed to come from my left hand (and that is the one with the intention tremor).
Thanks to a booklet put out by the Parkinsons Society, I found that Windows 7 has a voice recognition (or speech to text) facility built in. So I dug out a headset mounted microphone, and started to play. It works quite well in some things (Word, for example), but is not quite so good in this forum or my e-mail program (Eudora). This could be me, or the microphone, or the whole speech to text thing.
My guess is that if I had a lot of text to enter, it would be worth dictating into Word, and then doing a copy-and-paste to where I really wanted it.
If you wan to take a look, go to the Control Panel, and put Speech into the search box - and up it will come.
This might just be of use to someone.