YamiKaitou is correct. You don't need an AC or admin to answer this.
If you have the advanced package, then you can place the advanced ad anywhere. If you are on the Corporate package, then you need to place it on your page towards the top, where you don't need to scroll to view it.
This is more of a aesthetics question: what if the majority of users see it without scrolling (e.g., 1024x768 and above), but users with abnormally small (640x480, in some cases 800x600) screens must scroll down, but only slightly, too see it.
For example, certain computers at 800x600 will screw up the layout to where the content and left bar are separated instead of side by side, pushing down the ad.