You can usually view them in the BIOS menu (accessed by hitting some key during bootup; it should display a message to the effect of "Press <X> to enter BIOS" right as the computer starts up).
If you would like to see them in Windows, you will need to download a diagnostic utility. Sony may have one, or you could try MotherBoard Monitor (MBM), Everest, or SiSoft Sandra, all of which are usually capable of reading out the values from the onboard temperature sensors.