Peter / Leon - thanks I think you're right the rectangular crop seems to be the way to go. I think this proves the point that there's not correct answer to a question like this, it's all a matter of taste.
As an aside, on the back of this I've found myself a copy of Photoshop CS3 on amazon (Cs4 is just too expensive for my budget). I'm not too interested in spending a lot of time in photoshop but I'd sometimes like to be able to dodge and burn. Looking forward to having a play with it.
thanks for the help.