I found this but I don't know if it works. Some guy used this method with Windows 7 Pro.

Quote:

1 enable hyperthreading in B.I.O.S. 2 load up windows and CREATE A RESTORE POINT! 3 open task manager and click the PERFORMANCE tab, just to make sure it ISN'T working, if it is.... GREAT, but i doubt if it was that easy, that you would be reading this lol 4 click start, then RIGHT-CLICK the COMPUTER then click on MANAGE 5 click DEVICE MANAGER, then double click PROCESSOR 6 right click ANY of the listed processors 7 click UNINSTALL 8 it will say "warning you are about to uninstall this device from your system" click ok 9 click reboot now 10 repeat step 3... you should see all threads

This worked for someone else but not necessarily on a Dell.