Accesss Device Manager by typing devmgmt.msc in the RUN box, then hit enter. To the left of "Processors" should be a + sign. If you see 2 procs listed, you have a HT CPU. Another way is opening up Task Manager. If you see 2 graphs in Performance Tab, you have HT. Hope this helps.

See: http://www.intel.com/support/processors/pentium4/sb/CS-017371.htm