My recommended utility is CPU-Z form the CPUID people.
You can read the specs from their page. Essentially, you need a newer motherboard that has the features to allow CPU-Z to access the information.
Below are screenshots for my home WinXP SP3 Pro Desktop system are below so you can see what you get using this utility.
Click screenshots for better view
("HT" = Hyper Threading = near Due Core performance)