I never heard of Brightspeech, but I looked up some requirements for the Brightspeech voice.
Do you use one of the following OS's: "Windows 98SE, NT4SP6, 2000SP3, Me, XP, Mac OSX.2 and higher."
Is your computer at least a "Pentium III 500 Mhz, 256 Mb RAM"
or, if a Macintosh: a "Power Mac G3 800MHz, 256 MB RAM"?
Do you know if you have "MS SAPI 4.0a (Win32), MS SAPI 5.1b (Win32)" already installed?