The latest versions of both window-eyes and jfw, have OCR utilities built in
to them.
I don't know about nvda on that.
Docuscan does a fine job as an affordable OCR program.
Openbook and k1000 are great, but it is hard to recommend them any more,
because of their cost and limited advantages over more affordable options.
The other thing is how many more books are available than their were 20
years ago. I believe text cloaner pro will also OCR PDF files, but I
haven't tried that with windows 7.
http://www.readingmadeez.com/home.html
Howard Kaufman MSW LCSW