Mt sites have CTR of 5.5% the other is down http://visualcsamples.awardspace.co.uk putting ad units 160 /90 with red font color at the top is great thing for me bec it gives a clear idea about the site
On the left, place your ads in the same format and background color tables as the adlinks on the top. For your ad below, move it closer to the content of your site, where the visitors are most focused at.
Clean up the site and make it more web 2.0. Make a hor ad unit at the top of the content pages blending it in. Blend all your ads into the background