According to a report by famous tech news website
Winbeta, Microsoft has decided to phase-out the OEM editions of Windows XP by the end of this year despite consumers resistance to adopt Vista due to compatibility issues and hardware requirements. As a result computer manufacturers will only be able to sale Vista loaded Pc's.
By early 2008, Microsoft's contracts with computer makers will require companies to only sell Vista-loaded machines.
Despite Microsoft's relentless promotion of Vista, manufacturers are still seeing plenty of demand from customers for systems preloaded with XP, especially in the finicky SOHO market. For complete story, check the link provided