What versions of Windows support HyperThreading?

Answer 1

Windows XP and Windows Vista, Intel's Hyperthreading did not exist before these Operating Systems.

Now I may be wrong here, but I am confident that hyperthreading is a technology built into the processor itself, and any operating system should be able to utilize it. You are right to the extent that Hyper Threading is built into the processor itself, but a chipset and OS which supports hyper threading are also required. Here is the link which gives the list of OS which supports Hyperthreading http://www.intel.com/support/processors/sb/CS-017343.htm Windows XP supports HT Technology ,but widows and windows 9x/me does not

Answer 2

Windows XP, Windows Server 2003, Windows Vista, Windows Server 2008, and Windows 7 all have native support for HyperThreading. Windows NT and Windows 2000 will detect the threads as multiple processors, but performance may be worse than with HyperThreading disabled.