Why? Overture is the premier PPC vehicle available (US, at least).
1)Google traffic will be a fraction of Overture
2)Google CPC will, in most cases, be higher (by a considerable multiple,in my case)
3) Overture bid process is far more straightfoward
4)Overture reports run rings around Adwords Select
If you are just doing one PPC, then it really should be Overture. But don't take my word for it - why not use both? You won't know the strengths of one unless you've used the other.
You got it.