Thanks again Chris, it always good to get your opinion.
You're thinking of the wrong 70-300. I already have the one you are talking about. The one I'm considering is the brand new L series 70-300mm f/4-5.6 IS. It has only recently been released by Canon, a totally new lens, with the latest IS.
Here is a review:
http://www.canonrumors.com/reviews/e...-6l-is-review/
Definitely a different lens to the cheaper one's of similar focal length.
Cheers,
Jason.