Office XP supports speech. If you don't use Office XP, BUT use Windows 2000, XP, NT4 then here is a work around to getting Text To Speech (TTS) by using
Window's accessabilty Applet = Narator.
(See Narator image below)
Narrator is a text-to-speech utility for users who are blind or have impaired vision. Narrator reads what is displayed on your screen: the contents of the active window, menu options, or the text you have typed. To open Narrator, click Start, point to All Programs, point to Accessories, point to Accessibility, and then click Narrator.
To Use Narator within Excel:
All you need to do is set a reference in your VBA project to
[Microsoft Speech Object library]
Then in your code Dim as follows;

Option Explicit

Public Voice As New SpVoice

[Now to have Narator speak just use this Syntax:]

Voice.Speak "This is your text to speech text"
That's it!! ..................
Obviously there are a lot more Methods and Properties to use.
Have a look @ the screen shot below of a STD Userform example I have made up.