Here is the NVDA link
http://www.nvda-project.org/
I also use system access to go, which is taged to you, not to your computer.
veterans can get the full screen reader for free for life.
Anybody can get the web based version
http://www.satogo.com
The cool thing, is if you have a computer, sound card, and internet
connection using Internet Exploorer, you can independantly make that
computer talk with basic screen navigation and color choices. It's free and
it leaves nothing behind when the computer you are using is rebooted.