Nice placement but you can improve it also, on the top 1st ad, make its size to banner (468x60) , A link unit(vertical) can give you a big CTR if you place it on right panel.
Agree with mani the link unit at left will give a good CTR also you might consider not just replacing that current ad block with a banner but possibly placing another one through the content below possibly mid way down b/w two of the posts.
I can't place that banner size ad because my content plane have width : 430px. And spikey99 I have another ad between 3rd and 4th post
I would add a picture to the left of the ad - that will improve CTR for sure. Also consider trying to match the font size of the ad.
i think ads placement is just fine stick to it. you may randomly change the places of ads to see the difference in ctr. and try to use only those placement which gives high CTR.