http://openhardwaremonitor.org/
Simple, easy, nearly no memory footprint and a neat desktop widget. Gives you a nice graph of sensor outputs too. Worth a look.
Thanks for the input guys! So far, it seems like CPUID HWMonitor has the most comprehensive data. Some of the others are nice and concise but missing temps here or there. I'm not confident in my skills yet, so I figure more data is better!