As of version 1.5 of VoiceAttack, Windows XP can no longer be supported. The good news is that the last-tested version of VoiceAttack under XP can still be downloaded (VoiceAttack version 1.4).
Windows XP does not come with a speech recognition engine like Windows Vista and up. The installer for the Microsoft Speech Recognition Engine 5.1 is over 30 megs, so it was decided that a separate download would be made for it. What is suggested is that you first download and run VoiceAttack. If VoiceAttack does not find a speech recognition engine, you will get a link back to this page. At that point, simply click the, 'Download Additional Components' link below and run the installer.