#1 check in CPU Z under "CPU" for 2 things: a) the FSB should say 200mhz at stock. Since P4 is quad-pumped, that results in 800FSB and only HT P4s have 800FSB; b) the little Intel Inside icon will have letters "H" and "T" etched on the top right corner in it.
#2 Start --> My Computer --> Right click anywhere in the explorer Window and click Properties --> Click Hardware --> Click Device Manager --> Double click Processors (if you see 2 physical CPUs 2.4ghz each then you have Hyper-Threading enabled).
*** Note: option #2 might not work if you have Hyper-Threading disabled in the motherboard BIOS.
#3 Download Sisoftware Sandra 2005 (or any version):
then unde Information Modules click CPU&BIOS information
under first heading Processor --> check SMT support (check marked) 2 Unit(s)
under heading Features --> check HTT - Hyper-Threading support - YES