I'll try what you've suggest, and post my results back, I have some other questions but they can wait till later
edit: I've applied the changes you've suggested and started a 1280x1024 (decent render), I'll post up the finished one once it's done
edit: Changed done, dropped the contrast to 1.8 and also dropped the gamma, added in high cloud to break up the blue sky.
feedback greatfully accepted.