I think placement is ok... however I do have some suggestions how about a full horizontal leaderboard instead of a banner? and how about a banner in between each post? or a link unit? good luck
I would get rid of the 468 banner at the top and put a horizontal link unit there. It will look like a navigational bar on your site and will get clicked for sure. Additionally go ahead and widen that banner to a 160 instead of a 120. In my experience this has led to more clicks because of a wider space for text ads. I would also include a large square ad in your posts, which you content can hug. Putting in a 468 banner in between posts on the main page might also be beneficial. However, the less ad units you use the more money you will actually make, so I would encourage you to use the square for content, the link units at the top and a large 160x600 banner on the right. Then next month try something different and compare results.
In addition to what mainstreetcm recommended - do away with 468 X 60, use 160 X 600 instead of 120 X 600 on the sidebar. I suggest you use text ads only coz they convert better. Also, try putting ads in-between posts =>300 x 250 or 336 X can't remember) (my opinion though, based on what works for me)