Just a couple pointers:
1. There seems to be some trouble (as mentioned with others) stemming from your code. w3c validates with 30 errors ---
http://validator.w3.org/check?uri=http% ... online.com , and firefox shifts all of your main body content below your ads. Might be an incorrect float somewhere, or maybe a clear. Try to apply some quality assurance with your work, so that other users can rest assured to be viewing it the way you intended. Firefox is a primary target for such cross-compatibility, but there are several other browsers to contend with. Most of your problems will come from IE, as if firefox displays correctly, most others (safari, opera, etc) will also display correctly.
2. The blue borders around your ads are a bit unnecessary. Seeing as how they are ads, and righteously placed as such, the borders seem like overkill. Plus it doesn't really add to the layout, however minimalistic it is.
3. I see more and more of these target-oriented sites that only provide one sole service. I understand that these types of sites may not require as much design or style, but it's a problem to see a site as "another bandwagon jumper". The red header, the ill-placed logo with nothing to compliment it, etc. This seems like something you would find on a larger site, but I'm not quite sure it has a domain of its own, for simplicity i guess.
4. To continue with the validation errors, here is what I see:
No doctype (IE goes to quirks mode when this occurs. You give the browser basically nothing to work with, need to be sure you declare a doctype that fits the code you're using). Declaring a doctype may or may not also correct several of your other errors.
…ftsell/nph-softsell.cgi?item=13973-6&affiliate=344176"><img src="http://www.r
This is taken from w3c. You're using special characters in URLS and not the html equivalent. This can cause the information preceding the incorrect character to get thrown off. The & before a should be &. & is also safe to use in urls. This is done several times in your page.
…lv2video_120_90.gif" align="absmiddle"></A></a><br><br><br>
Can't use ABSMIDDLE as an alignment property for images. Top, middle, bottom, left, right are acceptable values.
Make sure you add alt properties to all your images. This is an accessibility issue, and if such is not declared, users who have images disable (unlikely, but possible) they will see nothing in place of the image.
You also have some improper use of div id's. In w3c it says you use "clear" several times. I assume this is a way to insert blank divs, but remember, you can only use # or ids one time in a specified document. Classes or ".class" can be used multiple times. Might want to redo the clear div to be <div class="clear"></div> instead of <div id="clear"></div>
I won't go into all the validation errors, but the ones mentioned above should correct 80% of them, and possibly even fix the problem you have with firefox improperly displaying your content.