I’ve played around with the PSCX script
Out-Speech at home and at work. At home, running Vista, words come out in a natural female voice. At work, running XP, words come out in a robotic male voice.
The voice is somewhat configurable. I didn’t try it at home, but at work I opened the Speech Properties applet in the control panel. All three are mechanical voices. I went to Microsoft’s web site to see if I could download a natural voice. The site said that Microsoft does not provide other voices but it gives a link to third party providers.
My guess is that Microsoft deliberately put lame voices in XP for fear of a lawsuit and that they were braver by the time Vista was released.
Another difference I noticed between Vista and XP is tolerance of misspellings. XP will correctly pronounce “Fahrenheit” but pronounces the incorrect “Farenheit” so that it rhymes with “heat” rather than “height”. Vista correctly pronounces the misspelled word.