Eric S. Raymond has an interesting article where he claims that 2008 is a hard deadline for an operating system to become the standard for desktop computing. With 64-bit hardware coming out there is an opening for any OS to become dominant on the new hardware platform and Raymond contends that by 2008 the de facto standard will be set and network effects will do the rest.
Steven Den Beste (fantastic surname :) ) has an interesting view on why Linux won't make it as the dominant desktop platform, comparing it to Christianity in the 17th century.
Disclaimer The opinions expressed herein are my own personal opinions and do not represent my employer's view in any way.