On June 30, Microsoft will officially stop selling its Windows XP operating system. However, the company will offer technical support until April 2009 and extended support until April 2014.

Due to the high demand from their clients, Dell, Lenovo and HP have decided to continue to offer Windows XP on the new computers.

Dell was the first to find a loophole in Windows Vista Business and Windows Vista Ultimate licenses. According to Dell’s website, the both editions of Windows Vista have “Downgrade Rights”. This means anyone who owns Windows Vista Business or Windows Vista Ultimate operating system can downgrade to Windows XP Professional.

Still, the clients who decide to opt-in for “Downgrade Rights” may use one operating system at any single point in time. They cannot run both operating systems simultaneously unless an additional license is purchased, Dell explained in a posting on its website.

“For customers who decide to exercise Downgrade Rights on their own, however, please note that Dell will only support the factory-installed operating system. Windows Vista Home Basic and Windows Vista Home Premium do not have this option, as they are not capable of downgrading to Windows XP,” the computer maker said.

Lenovo is using a slightly different approach. The Lenovo customers that have Windows Vista Business or Windows Vista Ultimate "qualified systems" may purchase a Windows XP Recovery CD until January 31, 2009.

“The Windows XP Recovery CD set provided by Lenovo does not require any online activation from Microsoft. It is as if it came on the system's preload and contains all required drivers, language support, and applications in addition to the Windows XP operating system software,” Lenovo announced on its website.

Similar to Dell, HP is using the same “downgrade rights” to sell systems with Windows XP until 30 July 2009.

Initially, Microsoft wanted to stop shipping new copies of Windows XP to computer makers on 31 January 2008, but it decided to extend the deadline until June 30.

Last week, Steve Ballmer, Microsoft CEO, reportedly said during a conference held at Louvain-La-Neuve University in Belgium, that the company could reconsider its deadline. However, the company said it has no plans to extend the availability of its successful Windows XP operating system past its announced deadline.

"Our plan for Windows XP availability is unchanged. We're confident that's the right thing to do based on the feedback we've heard from our customers and partners," said Microsoft in a statement.

On April 29, Microsoft will release Windows XP Service Pack 3 via Windows Update and the Microsoft Download Center. The service pack includes previously released Windows XP updates, including security updates and hotfixes. It also includes select out-of-band releases, and a small number of new enhancements, which do not significantly change customers’ experience with the operating system.