Adsense and Blogs

In an article on Adsense: Why Bloggers Don't Get It Greywolf wrote: 'If you want people to click on your ads, you will need put them where they can see them, above the fold in the center of the screen, in a prominent location...' That makes pretty good sense, when I was using standard web page layout I had a large Adsense ad starting placed at the beginning of the second paragraph with the text wrapped around it and it did pay more than other ads!

Currently I'm experimenting with a magazine type blog - snippets with a thumbnail on the home page plus a large version of the image on the actual page itself.

So question what code should I use to insert a large rectangle ad 300x280 into my article and what file would I need to place this code in. It would be important to have the ability to override the layout, say if you had a very short post and the ad would stick out like a sore thumb.

Ideally I would want it to appear on the left hand side of the page, if possible starting at the beginning of the second paragraph with the text wrapped around it. If not possible then starting at the beginning of the article.

Any suggestions