I couldn't see where you might have added a top margin to increase the space. The styling indicates you used a top relative position of 8px to shift the text down.
Different browsers don't always have the same default margins and padding for the same elements such as divs or paragraphs, so you can explicitly set the margins and padding in such cases to make them look more alike from one browser to the next if needed.
I would suggest you use this styling for #main-text instead of what you currently have. The top and bottom margins still won't be perfect, but it's closer and the text at the bottom of the page won't disappear the way it is in IE 6.
#main-text {
margin-top: 10px;
margin-bottom: 10px;
margin-right: auto;
margin-left: auto;
width: 770px;
}
Setting the left and right margins to "auto" will center an element in the window or parent element as long as the element has a width. Do the same for the other elements on the page which need centering like this:
#flags {
height: 67px;
background-image: url(images/flags.jpg);
background-repeat: no-repeat;
margin-left: auto;
margin-right: auto;
width: 770px;
background-position: right;
}
#header {
color: #918231;
font-family: Helvetica, Arial, sans-serif;
font-size: 0.8em;
padding-bottom: 10px;
text-align: right;
margin-left: auto;
margin-right: auto;
width: 770px;
}
#inner-image {
height: 506px;
background-image: url(images/centre_image_1.jpg);
background-repeat: no-repeat;
margin-left: auto;
margin-right: auto;
width: 770px;
}
There are four validation errors on the page as well which you should fix.
Since you are using xhtml, your opening html tag should look like this:
<html xmlns="http://www.w3.org/1999/xhtml">
The very last closing div on the page should be removed because it doesn't go with anything. There's no opening div for it to close.
Also, your two anchor closing tags, </A>, should be lowercase since your page is xhtml.