I have been running few campaigns on both Google and MSN and noticed that each is providing you with and estimated traffic / impression / clicks based on the level of CPC you are willing to pay. At times the estimations seems to be rather wild to me so I was wondering how much can one rely on them? Surely both big G and MSN are trying to earn most of the dough for themselves so perhaps they try to encourage each customer to pay the highest CPC possible. Hence I would question their estimates at any day. What is your thoughts? Any experiences / relevant comparisons?