Hmm, well it says about the newest version, 4.32, "Not to mention that the driver that allows SpeedFan to fully support even Windows Vista 64 bit is now signed with my digital certificate." http://www.almico.com/speedfan.php
Edit: Core Temp may work if you just want temps, it has to be run as administrator in vista to get it to run. Not sure if it will work on the 64bit vista. http://www.thecoolest.zerobrains.com/CoreTemp/