I know it may seem odd not to be allowed post a url, but honestly nobody needs to see your site. I would have made just the same comments, though obviously inserted 'maybe' a few times, if you had just described your site.
I mean just what I said - I did not notice them at first, that is a fact. I did see them after looking at 3-4 pages, but not right away.
Yes, which means they look too much like classic banner ads, I have long since stopped even noticing those, as have many internet users. They are sat neatly into a header which I just thought was a page wide header, or to be more accurate I formed that impression without thinking at all, which is they way most people look at pages.
Everything needed to navigate through the forum is well below the ads, so you never have any need to look up again and see them once you are in the site - and if that is the case for a first time visitor (me) it will be even more so for a regular one.
I think you are referring to the heat map - which is here https://www.google.com/support/adsense/bin/static.py?page=tips.htm - and if you take another look you will see that the extreme top right - where your ads are - is white, not a hotspot at all.
Top/bottom of the "page" refers to above and below the content, which are among the hottest spots.
I would just try putting them in either of the following ways for a few days - or even both - and see what effect it has:
a. Where they are, but on the orange background with no borders etc. Might make some difference.
b. Between the forum navigation and the messages, perhaps directly on the orange again or maybe on the same color background as the forum navigation itself. I think this would make quite a big difference.