Error: "The referenced assembly is not installed on your system" Vista Speech error

Hi just bought a machine with Vista Business and Office 2007 pre-installed. But there is a problem, then I activate text to speech in the control panel I get the following error "The referenced assembly is not installed on your system"

Anybody here knows this error? if yes then why Vista gives me it only then I try to activate text to speech?

Best Regards
Fred