More accurately, your AT&T Natural Voices version will not install on Vista. You probably got an error message that says something like "The operating system is not adequate for running AT&T Natural Voices." This problem may also affect people with Server 2003. Chances are, however, that it will actually run just fine after you get it installed. The problem is you got your disc from a company like ReadPlease that does not have an updated MSI file because they no longer deal with AT&T, and AT&T is about as sympathetic to your problems as they are when you try to deal with their phone and broadband customer service about their sleazy practices. I would just post the fixed MSI, which is only about a megabyte, but I think it is copyrighted material or something, and I don't want to stick my neck out to find out if I am a big enough fish for AT&T to come after.
The actual alteration that needs to be made to the MSI file is so simple it is a joke. Yet AT&T apparently has no intention of releasing an updated MSI file to allow you to use what you already paid for, even after repeated requests. Hmm. I wonder if they just want you to spend another hundred bucks and don't care if they are being fair. Anyway, I may sound negative, but once you see how easy the fix is, you will probably be disgusted, too.
The biggest problem with the fix is the long download from Microsof of their SDK suite of programs. All you need is the Orca program, but you have to get the whole package. It is a free download, but it might take you two hours to get. Get it here. If you know of an easier way to edit MSI files than to download Orca with SDK, use it. Orca unpacks with the SDK package, but you have to go find Orca.msi and double click it to install. Then, just launch it from the start/programs menu.
Now, obviously, you will not be able to change the natural voices MSI file on the CD media itself, so you will not be able to install it from that location. So, make a directory on your hard drive, for instance on the desktop, and copy all the files from your installer CD into it. Now, open the MSI file in Orca. Once the MSI file is open in ORCA, click on the LaunchCondition table. The tables will be lined up along the left side of the program window. On the line of the LaunchCondition table that has all the OS versions on it, add this to the end of the line if you have Vista: OR (VersionNT = 600) If you have Server 2003, add OR (VersionNT = 502) There is a list of codes for different Windows versions here that you will probably not need. Now, just close, save, and run the Natural Voices installer from the directory you created on your HD. Bingo.
Oh, and DON'T FORGET TO BURN IT TO A CD! You know you were going to blow that part off.
I have not tried this on the premium voices discs yet, but I betcha it is just as simple.
Well, that's it. I would seriously love to hear if this helped you, so please
let me know if it did here 
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