Only Windows 64-bit Platform OSs are currenlty supported (since version 2.5). Please see the list below:

• Microsoft® Windows Server 2003 (Standard, Enterprise and Web) 64-bit
• Microsoft® Windows Server 2008 Enterprise 64-bit
• Microsoft Windows XP (Professional) 64-bit with SP3 or later
• Microsoft Windows Vista (Business and Ultimate) 64-bit
• Windows 7 (Professional, Enterprise and Ultimate) 64-bit