I switched to using TP Fan Control a few months ago and it is a great help. However, I can report positive results

I downloaded a Firefox plugin that forces all YouTube videos to use HTML5 rather than Flash and I now have the following temperatures:
35C-40C Idle system with nothing running
45C-48C Browsing the Internet using Firefox, playing a DVD at 720p or watching an AVI or MP4 video
51C-55C Watching a YouTube video at 720p
So, a drop of at least 20C in CPU temperature just by changing to HTML5, much better

If anybody else wants to try the plugin it's called 'Youtube ALL HTML5 2.1.3'