Min-Height With IE

ok, i am getting extremely frustrated with this.

i have a "mainbody" class which contains the border and such for the main website. then inside that i have 3 columns. i used all divs, no tables.
sometimes the div's content is not long enough to cover the sidemenu height, the minimum height, which is about 400. so i used min-height:400px;. seems appropriate. well it immediately worked for firefox. but it is NOT working for internet explorer and i have tried so many things including everything on this page:
http://www.dustindiaz.com/min-height-fast-hack/

Can someone please help me?
The question: how to get a minimum height using internet explorer.

* html selector {
height:400px;
}
Where selector is the element that you want to have the min-height. That will only target IE6 and below. IE7 understands min-height.

i am afraid that IE7 does Not understand min-height!

Yes it does. If it doesn't then its likely that you code is invalid in the first place. IE7 doesn't understand min-height if a partial doctype is used or if no doctype is present. Post the rest of your html.