Positioning block-level elements with custom fields?

I’m building a 4-column theme from scratch. The designer’s layouts require certain chunks of content on a Page be positioned in specific locations. For example, a list of links in “A,” a image in “B,” and a copy block in “C.” Please view my screen cap for reference: http://screencast.com/t/NDMyMTA4Y

The less skilled way do this would be to build a different template for each Page, and just hard code the content into the HTML. But I’d like the admin to be able to choose where content is positioned via the Edit Page screen. Is there a way to do this with custom fields? Or a magic plug-in?

Any feedback, links or tips greatly appreciated.

Thanks,
MT