Microsoft has begun shipping the latest versions of Windows Vista and Windows Server to manufacturers. Both are expected to be made available to customers next month.

Windows Server 2008 will be the first new version of Microsoft's server operating system since 2003.

Known by its Longhorn code name until last summer, Server 2008 will sport improved security and new features designed to improve stability.

"It is an exciting day for us and an exciting day for our partners and customers," wrote group programme manager Alex Hinrichs on Microsoft's Windows Server Division Blog.

"We have all been working towards this day for the past three years and over 5,000 people have contributed to this release."

Microsoft Volume Licensing costumers, or those with Microsoft Software Assurance or an Enterprise Agreement, will be able to download Server 2008 and Visual Studio 2008 in late February as part of a special event called Heroes Happen Here.

All other users will be able to purchase Server 2008 on 1 March.

Users will need to wait a bit longer for the first Windows Vista service pack, however, which is now slated for mid-March.

Windows Vista SP1 offers stability and compatibility updates, but some researchers have disputed Microsoft's claims of increased performance.

Users will be able to download Vista SP1 in mid-March. By April, most users will be able to get the service pack as an automatic update.

There is one group, however, which will not be able to install the new version of Vista.

Microsoft said that a small group of hardware drivers are still not compatible with the new software. Those users will be able to download the update as the drivers become available.