Windows XP is by no means dead, and the fact of the matter is that the operating system released at the end of 2001 is still positioned as a valid alternative to Windows Vista. On the Microsoft's official webpage reserved for obsolete products, Windows XP is nowhere to be found. In fact, the latest version of the company's operating system considered obsolete is Windows 3.0 Standard Edition. But Windows XP will continue to be available via retail and original equipment manufacturers until the end of January 2008, and then to system builders until February 2009. Before
Windows Vista even hit the shelves in January 2007, the company announced that it was expanding support for some versions of XP, to match that of Windows XP Professional, meaning 2014.
In this context, it is not surprising that both home and corporate users are willing to ride Windows XP for everything it’s got. While some have announced drastic measures such as waiting for Windows 7 (Seven), Vista's successor in 2010, others are simply waiting for the first service pack for the operating system, due in 2008. And preparations for Vista deployment are late to say the least. This is the main reason why corporate clients choose to exercise their downgrade rights with Windows Vista and stick with XP.
Although in Microsoft's vision Windows XP is at least expired if not obsolete, the Redmond company has simplified the Vista to XP downgrade process. In order to exercise downgrade rights, users first have to acquire the operating system, and in such a case, even if they run XP instead, the clients' trajectory will still evolve to the Vista destination point. But while Microsoft has traditionally made it easy for Software Assurance customers buying Vista through volume license to downgrade, the process has also been streamlined for OEMs offering the Business and Ultimate editions of the platform.
PC makers such as Fujitsu, HP, Dell, Acer and Lenovo have started including new machines with Vista preinstalled CDs with Windows XP Professional at almost no extra cost. Downgrading a Vista computer to XP also no longer requires any additional activation, if the original installation of the operating system was pre-activated, which is general OEM practice.
source: softpedia