Hi Jenny
Perhaps things have changed. I'm not sure. But a few versions back when you needed to install Text To Speech, what you actually downloaded and placed into a folder was just a file that you later ran. When running the file, it somehow deduced the Captivate installation folder and placed the content where it needed to be.
So unless someone pops in to refute this and say "it always needs to be downloaded in this folder", I'm going to say the choice of folders likely doesn't matter much.
Cheers... Rick