Topic : Display mess up with Internet Explorer 7

Hi, well my display is ok with Firefox, Chrome and Internet Eplorer 8 but with Internet Eplorer 7, it's the total mess. The div are acting weird. If I put a margin, it doesn't count it, if I use a float for a div into another div, it goes out, even a php while to display some data into a text goes wild ( go to the next line after each record while the source code doesn't show any problem at all ).
Such a shame that I have to adapt my code for a out of date browser but so many people still using it.
If somebody knows how to fix that problem, I'll be glad