If I buy AdWords, will that cause my algorithmic search rankings to rise?
There’s no boost. There’s nothing going on in the algorithm there, where if you buy AdWords you will rank higher in Google’s organic search results. So don’t count on that. Instead, try to make compelling, great content – the sort of thing that attracts links because it’s really excellent. Don’t count on buying AdWords to cause your organic rankings to go up.
by Matt Cutts - Google's Head of Search Quality Team