Where can I get voices for .net applications using System.Speech in Windows 7? [closed]

I'm so confused between the text to speech technologies in Windows. I have a slightly peculiar requirement: I need to output speech from a .net program running in Win 7 using System.Speech assembly. I want a good, robotic sounding voice that doesn't have as strong a US accent as Microsoft Anna.

Which 3rd party voices will work with the .net api? Does anyone know of a good British (but not too British) voice, preferably free or cheap?

How do I get more voices for Windows 7?

In settings, go to Time & Language -> Speech and choose a voice from the dropdown menu. The chosen voice will be used to read text aloud. Don't like any of the installed options? Add new ones using the Add voices button below.

I believe the current TTS engine uses SAPI5 voices. I have not played with TTS beyond SAPI4, but some searching for "SAPI5 voices" produced relevant links. Perhaps this can take you further and actually find the voice you're looking for?