I was using
Acapela's High Quality Text to Speech Voices 'Acapela Heather' in Vista (32bit) successfully. After upgrading to Windows 7 Ultimate (32bit), Windows no longer lists Heather in the 'Voice Selection' dropdown box of the 'TTS' menu under 'Speech Properties' from the 'Control Panel'. Reinstalling the voice has not helped. Acapela is listed under Microsoft's 3rd party TTS Engine ...