Welcome to WebmasterWorld Guest from 126.96.36.199
When you think about the logic here it flies in the face of history. People taught themselves to ignore banners en-mass because they found them intrusive and annoying. This is not so with adwords because rather than being untargeted ads, they are very much on topic.
I think as time goes on, more and more people will desert the natural results in favor of the ads because of this excellent targeting.
As you can see in mine I started to clean up indexed URL's by adding some disallows to robots.txt for layered navigation etc.. then after the update it's jumped from around 130,000 to 205,000.