Hello
You can see what I'm discussing here: http://www.craigatkinson.co.uk/category/news
as you can see, the text trails to the end of the page. What I would like is for the text to sit within a space of about 600px. I tend to use 700px wide images in posts and would like the post text to come just short of the image.
I can't set the blog to a max width because by doing that the left sidebar will no longer be flush with the left of the window.
Is there a way I can do this?

I assume you mean the 'edge' of the page as opposed to the bottom which I take to mean the bottom of the page

Technically the text and images should all be part of the center area and how wide it is. one idea is to add a right sidebar, that is 100px wide, put in a single text widget (to prevent the default widgets from showing. and not the text should stop at the 600px wide center, but the image 'may' overlap the sidebar

doesn't hurt to experiment.

You could use a table or divs.