Once you've paid for the doubletalk lt, you have at least two choices for screen readers that will run in dos. One of them provox was written by a speakup list member and is free for download. Then there's jaws for dos also free for download since it like provox are no longer supported. Provox though isopen source though. Jaws for dos has to be searched out on the ftp links. One more thing, if you have at least win2k you don't need win-eyes trial anything for speech. Thunder screen reader is available free for download for personal home users and nvda which recently had an update is also available free for download and it's open source. nvda is written in python and may get improved to where it can work with openoffice if the interest is there among the developers.
