I wrote an app in C# for speech recognition using System.Speech which works fine on Windows 7.
However I\'m after creating the same app that will work on windows 2003 (x86).
You're creating a speech recognition engine without specifying an engine. Since you've installed the en-GB engine, you need to specify a cultureinfo (or a recognizerinfo):
sre = new SpeechRecognitionEngine(new CultureInfo("en-GB"));