Windows 7: Narrator Win7 - Change voice (more detailed Q)

Ok, I've been checking around the various forums for Windows an all the different versions for one simple question, but no one seems to be asking it the right way.

So, we all know that windows comes with a built in Narrator, a text to speech program that reads everything an has the default voices, an most people will change the pitch, sound, an speed of the narrator. But what I wanna know is if there is a way to REALLY change the voice from Anna to someone else
(Ex. You change the voice of the narrator from Anna to George W. Bush).

This is what I am asking, I already know how to change the pitch, speed an whatever with the default options for narrator, I just want to know how to change the voice or at least add a new voice to Windows. I know there's sound files out there that people use to create voices of their own an make funny recordings, but I wanna know is if I can add a voice file to windows.

Those that KNOW how to tweak or modify small bits of windows without screwing up the system or causing a CRI (Copyright Infringement) to occur. I'm not looking for illegal modifications, just lil ones that'll improve the enjoyment I can experience on windows (its no different than adding a new weapon to a game like Halo or Crysis).

Thanks in advance to anyone who will help me out

Welcome to the Seven Forums
I have been googling this and I am sure you have to unless I missed something it looks like you will need a 3rd party program to do this. Maybe someone else will know?
Sorry
Jerry

Have a look here:
Changing Windows Narrator to use a different SAPI5 voice from Microsoft Sam

-DG