If you are running Vista Beta 2, check out the new text to speech functionality using the Narrator screen reader program. (Narrator is also enabled in Windows XP; however, the Vista TTS voice is way better in terms of naturalness and intelligibility IMO compared to MS Sam).
You can start Narrator in one of two ways.
1. If you have the "Run" command enabled in your start menu. then go to START > Run > and type "narrator.exe". (Egads, no, the 'run' command is not there by default. To get it there, right click on the toolbar and go to PROPERTIES > click on the START MENU tab > click on the Customize button and then find the check box for the "Run-command on".)
2. Or, simply go to the control panel and click on "Ease of Access". There you'll find the "Narrator" button to get you started.