Thanks Flake, I think the key is Image quality as you pointed out.
I occasionally do try to photograph wildlife but that is more by accident than deliberatley setting out to take it but I think the 5D is more than up to this.
I had concluded the 5D would be the one but wanted other opinions, I also came to the conclussion that if did go for the 7D that A) I would always hanker after the 5D and B) I would end up buying new lenses anyway so it is better to spend a couple of 100 more.
Also current owners of the original 5D I have spoken to are still happy with that camera which is surely a good sign.
Coincidentally a colleague of mine has just bought the 5D MK II his primary reason for that was the Video in his case I think the 7D would have been the better option as it has a lot of control and flaxability in this area. I did get to play with it though and felt at home straight away as the layout and controls were very similar to my 40D, looking through the view finder was amazing it felt like I had been looking through someones letter box with the 40D.
So now time to start to try and find the best prices