Java ES5 Update 1 supports the following versions of Microsoft Windows:
Windows 2000 Advanced Server SP4 and Data Center Server SP4
Windows 2003 Standard SP1 or later for x86 and x64 platforms, Windows 2003 Enterprise SP1 or later for x86 and x64 platforms, and Windows 2003 Data Center Server SP1 or later for x86 platform
Windows XP Professional SP2
For the supported editions of Windows 2003, Sun recommends that you use SP2 or later.