Most "modern" (socket A and P4 motherboards have both the hardware and software required for temperature monitoring.
The exact location of the screen in BIOS settings varies by motherboard mfg.
For some, there is a PC health screen.
For others, it is a sub-memu in the Power management section.
Many motherboard mfgs. also provide a utility to view the temperatures and fan speeds from within Windows.
For ASUS motherboards, the utility is Probe.
Here is a link to a donate-ware program that allows you to see the motherboard monitor information from Windows.
http://mbm.livewiredev.com/
Chas