Core Temp is a compact, no fuss, small footprint program to monitor CPU temperature. It shows the temperature of CPU in your system. Also,It's completely motherboard independent.
Now Core Temp supports Windows Vista and Windows 7(including x86 and x64).
Its CPU Support list:
All AMD K8 CPUs are supported starting with the early SH-C0 stepping and up. The latest 65nm BH-G1 and DH-G1 revisions give inaccurate readings.
Intel CPUs based on the 'Core' architecture, meaning all CPUs on the Core Duo/Solo and Core 2 Duo architecture.
But Pentium 4/D CPUs are NOT SUPPORTED!!!
Download Core Temp 0.99.4 here:32 Bit 64 Bit
You can check the checkbox to make Core Temp start together with Windows.