Many thanks to those who provided tips with my first image, i think I have got the hang of where to position the altitude settings of my different layers.
This is my second image (that I have been happy enuf with to post) - I am not happy bout the detail level along the ridge in the foreground, to me it looks like it has lots of artifacts in it, but I had the AA settin up around 7 and the detail slider about half way along. Am I imaging things? how can I make it sharper and crisper?
http://www.flickr.com/photos/thebluerose/2446083581/
Well, it's bit small to see any artefacts, but with the detail at half, set it to 0.8 or 1 to get the best quality...
It needs to be bigger, like Mohawk20 said.
Not quite sure if I have attached my images correctly but I have modified the first image, made lots bigger, and added some clouds and atmosphere (which I had forgotten!)
I don't see any artefacts to be honest...
I took your advice Mohawk and upped the detail to around 0.8 ish (sent my rendering time from 1 hr to 5.5 hrs) and that has made a VAST improvement in visual quality, so thanks for the tip.
Glad I could help...