High Idle CPU temperature under Ubuntu, but not Windows

It is not really an anwser more a proposal how to proceed. For me it seems impossible that a CPU that is idling should produce a heat of 72 degree celcius. Do you mean by idling on the os is running or did you check the load of the CPU?

Install powertop from synaptics and start the programm in the terminal by "sudo powertop" the programm will tell what the CPU is really doing. It tells you also which activities keeps the CPU busy.

Have you checked your CPU Frequency?

Usually my laptop only heats up when the frequency is higher than normal for extended periods.

You can control the frequency by adding the "cpu frequency applet" to the panel (if you are using gnome).

Install jupiter, either jupiter or acpi=off, it completely stopped my power hogging problem.

acpi= off stopped most of it but with jupiter installed it has never come back. The freq scaling applets don't always stay on the panel for me.