my site views perfectly in firefox 2 and ie6 but if i view it in firefox 3 it doesnt display correctly.

here is the link to my site http://zachsim.jolyza.com/

In style.css, within the block starting on line 5, remove the line:

display: inline-block;

P.S. Firefox 3 has better CSS support than Firefox 2. It passes the acid test 2

1 - you need a "wrapper" div to hold everything else
2 - text-align: center is NOT the way to achieve a centered layout in anything but legacy IE versions. Use CSS, apply a width on that wrapper, and use margin: 0 auto; to center it.
3 - When you float an element, you MUST give it a defined width - which you have not done.

text-align: center was to center text/images in header and footer

Ok, then you don't have anything defined in the code I saw that would properly center a div.

Although the quick fix I gave above will work, Lady is right. You should take a more structured approach with your code. You need some basic structure so that it will be easy to add lots content, or make changes, in the future when and if you need to do so.