Personally, I think that visitors will become blind to the banner in the header. I don't think you'll get many clicks on that. I'd also have something like a 250x250 immediately after the heading in every post. You'll have to write more text, though, so that Adsense can determine what the content is about and then deliver targeted ads.
I disagree, I think thats a good spot to generate clicks. I said so because my first impression was to take a look at it. Moreover, your site is good it seems more professional than most of the one here, you have a lot of space get a text ads 160X600 in that area.