No doctype, so you have designed to IE Quirks Mode.
http://hsivonen.iki.fi/doctype/Maybe a box model problem. In Quirks Mode IE uses its own, old box model where padding and borders are included in the width. In the standards box model, width is only the content width, whatever padding and borders are added outside that. So if you have padding, the box would get more narrow in IE Quirks. The page breaks terribly in IE with a doctype that triggers Standards Mode on.
If you excuse my ascii art, this how the display of a box with a certain width, border and padding would differ.
CODE
@ border
x padding
Box model according to W3C
|---------- width ---------|
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx@
@xxBlah bla blah... xx@
@xx xx@
@xx xx@
@xx xx@
@xx xx@
@xx xx@
@xx xx@
@xx xx@
@xx xx@
@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx@
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
IE's old box model
|---------- width ---------|
@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@xxxxxxxxxxxxxxxxxxxxxxxxxx@
@xxBlah bla blah... xx@
@xx xx@
@xx xx@
@xx xx@
@xx xx@
@xx xx@
@xx xx@
@xx xx@
@xx xx@
@xxxxxxxxxxxxxxxxxxxxxxxxxx@
@@@@@@@@@@@@@@@@@@@@@@@@@@@@