free copy of good dictation software for disabled?

I have XP sp2 I only have the use of one hand, and I need a better voice recognition program than XPs. I tried to dictate it to enter a novel, I am now writing. Even spend the rest of the money I had on a micro expensive (filter background noise supposidly) However, when I speak, always XP types absurd, and I must restore my document from the backup. I tried ethe trial "talkittypeit" This is not accurate (it kind of bad thing, a pop up and said "this is not true, unless you buy the program), I my doctor thought to pose a prescripe note for a good program, perhaps that health care will pay for it, but I am confident because Tennessee is not paying for nothing Please help! You're contribution is greatly appreciated! "Have a nice day