Windows XP SP3 Now Available For Public Download

After a series of delays, Microsoft has released the last major update for its Windows XP operating system to broad distribution.

Windows XP Service Pack 3 is available from Microsoft's automated Windows Update service or as a file that can be pulled from the Download Center on the company's Web site.

Microsoft had planned to broadly offer Windows XP SP3 earlier, but the release was delayed by a series of bugs -- including one that rendered the update incompatible with PCs that have Microsoft's Dynamics Retail Management system installed.

Microsoft is now offering a patch that resolves the conflict.

The service pack should offer a number of enhancements over the current version of the OS, which Microsoft is phasing out after June 30. It includes all updates issued since Windows XP Service Pack 2 was released in 2004, as well as some new elements.

Among them: a feature called Network Access Protection that's borrowed from the newer Windows Vista operating system. NAP automatically validates a computer's health, ensuring that it's free of bugs and viruses before allowing it access to a network.

Windows XP SP3 also includes improved "black hole" router detection -- a feature that automatically detects routers that are silently discarding packets. In XP SP3, the feature is turned on by default, according to Microsoft.

Additionally, Windows XP SP3 steals a page from Vista's product-activation model, meaning that product keys for each copy of the operating system don't need to be entered during setup. The feature should prove popular with corporate IT managers, who often need to oversee hundreds, or even thousands, of operating system installations.

Some users may balk at a feature in XP SP3 that prevents them from downgrading their browser from Internet Explorer 7 to the older IE 6 once the service pack has been installed. XP SP3 also won't install on systems running beta versions of the yet-to-be-released IE 8.

Microsoft said the restrictions are designed to prevent system instabilities.