Microsoft has changed the code name of its next version Windows operating system. Previously called Longhorn, the first test version of Windows Vista will be released to developers and information technology professionals by August 3.

Microsoft said it will release two test versions but gave no indication of when the second would be offered to a wider audience.

The new operating system will be designed with security improvements designed to protect PCs against viruses and spyware. Other features confirmed by Microsoft are broad IPv6 support, improved client-side caching of data stored on a server, whole-volume encryption and a secure boot-up process designed to protect your data if your PC is lost or stolen.

"The core idea around Windows Vista," said Brad Goldberg, Microsoft's general manager for the Windows product, "is bringing clarity to the user so they can focus on what matters most."

The software company said it is still on target to release the Windows XP update in the second half of 2006.