O.K.
Now to explain the value of being 1st, 2nd or third.
A good portion of traffic you receive will not be from google. It will be from it's partners, like Lycos, Netscape. Here's why...
On google, your adword campaigns show up on the right hand margin. On the search partners, they show up as sponsored links, BEFORE any of the other links. But, to get here, you have to be in the top positions on google.
Now here's my "exclusive" secret. Say you get in one of the enviable top positions. Then at about 7:00 p.m. EST you decide to tweak your ad a bit to increase clickthrus and conversions.
If you can wait...don't do it. Here's why. Before an ad will appear on a partner's site, it will be MANUALLY approved by a google adwords specialist. So, even if you were already on the partner site, google system detects the change, put's up a red flag, and removes your listing from the partner listings UNTIL it is manually approved.
When will this be done?...some time after 8:00 a.m EST. So, your site loses it's position for the whole evening. I personally try to limit my changes on top performing keywords to about 4:30 p.m. EST or earlier.
But, I am just scratching the surface here. So far, these have all been secrets that I learnt by making Google Adwords a crucial part of my advertising buying strategies.
I can't stress enough that there is a mountain of information available through experts like
Perry Marshall. And using the right tools. (I've provided the links in posts above).
Hope this helps!