Thanks njeneb and MacGyver... I do know about the cross hairs for moving the sun... the issue lies with placing the sun accurately between branches and leaves. I have to move the sun a tad and hit render (crop render) and so on until the sun is in the correct place. I have a new one rendering at the moment at home on my macbook pro (I'm certainly getting my monies worth from this computer).... but this will probably be a couple of days. And Mohawk20 this is at full competition size, so the detail should be good. I'll keep you posted.
Cheers,
Simon.