Hi tarik916.
If the way the page appears in IE is how you want to to work, then your problem is that Firefox is correctly setting your page width to 800px, as you have set it in your CSS:

---------------------

#container {
height: 600px;
width: 800px;
etc.}
---------------------

IE, however, is (incorrectly) increasing the width of #container according to its contents (i.e. all the 'm's). This is making your container reach roughly 947px in width.

If you would like the page to expand as your content expands, then the first thing to try is to remove the width property altogether. Also, putting a really long line of letters without a space isn't a good way to test a layout, because it often ends up overflowing its containers, and also, you're not likely to have such a long word without spaces when the site is complete :)

Let me know how you get on, or if this is unclear.

Ben