Our sources have told us that Larrabee might not have Windows XP drivers and that the software team will only focus on Vista and Windows 7.
Since the first products will go after the professional market it's
highly likely that we will see a Linux driver as some of the
professional guys use Linux; but from what we know there might not be a
Windows XP driver.
Intel simply wants to move away from this operating system and invest
its development time in the future, which is obviously Windows 7. The
Vista driver is reality, as this operating system is gaining market
share as we speak, as most of the systems do come with Vista and you
almost don’t have a choice to go back to Windows XP, especially when
you buy your PC in a local retail store.
Desktop / gaming Larrabee will probably come much later after
workstation, simply as workstation driver is complex and hard but at
the same time you only need to optimize OpenGL, as this is what most of
the workstation software uses, while in gaming DirectX plays a much
more important role.
Source : http://www.fudzilla.com/