The whole sdk is still somewhat overdone...
Check:
http://www.msagentring.org/setup.htm
Youd should need:
Install the Lernout & Hauspie TruVoice,
Text-to-Speech Engine (English version) (1MB).
and the language of your choice (British English sounds way better then the american english).
Is there a speech icon in your control panel then I suspect it isnt needed tho, and as far as I remember XP has that. Anyway this would save you an enormous sdk download.