At first I found that your code on my IE6 was showing the two columns side by side. I loaded your images one by one until the right column dropped. It was due to pic_delivery.jpg wich is 224* 148px.
#left is 301px wide but .subhead has padding 24px right and 58px left. The image 224px + 58px left = 282 + 24px right = 306px, wider than 301 in #left so it's too wide and #right does not have enough room as the whole #container is 602px wide.
So alter the padding, perhaps the right side as it's less noticeable there:-
.sub_copy {
position:relative;
padding: 3px 19px 6px 58px; /*was 3px 24px 6px 58px;*/
}
Code downloaded to my PC will be deleted in due course.
WIN7; IE9, Firefox, Opera, Chrome and Safari for Windows; screen resolution usually 1366*768.
Also IE6 on W98 with 800*600 and IE8 on Vista 1440*900.