Just for the record, I have a great program called SpeedFan that I use. It detects HDD, CPU, and my case temperatures, as well as voltages and you can select one temperature to sit in your taskbar while it is running.
The best thing about it is: it's tiny! It doesn't take up practically any system resources. Under the task manager, it's taking up about 2,000 kilobytes of memory. I'm not worried.
Here's a link: http://www.almico.com/speedfan.php