<edit>One more thing, be sure to track your ads. Before I did this I thought my Overture ads were outdoing my AdWords but I have since proven that wrong. Know where your traffic is comming from, this will help you to target the audience you want.</edit>
I agree, tracking is critical. How are you tracking Google ads? My issue with tracking is that I cannot tell which keyword the search was for without matching to the logs, because all keywords are connected at a campaign level. With Overture, I can track each keywork like:
so that I can quickly tell which keywords are turning into sales.
It is mostly this ability that causes me to favour Overture.