Attached Link: http://www.intel.com/support/platform/ht/os.htm?iid=ipp_htm+os&

This is from the Intel web site... Microsoft* Windows* Operating System Desktop Based PCs The following desktop operating systems include optimizations for HT Technology and are currently eligible to carry the new Intel Pentium 4 Processor with HT Technology logo: * Microsoft* Windows* XP Professional Edition * Microsoft* Windows* XP Home Edition The following desktop operating systems are not recommended for use with Hyper-Threading Technology. If you are using one of the following desktop operating systems, it is advised that you should disable Hyper-Threading Technology in the system BIOS Setup program: * Microsoft Windows 2000 (all versions) * Microsoft Windows NT* 4.0 * Microsoft Windows Me * Microsoft Windows 98 * Microsoft Windows 98 SE