Start by using a fully qualified doctype declaration, and get rid of the empty line before it at the start of the document.
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
Make sure that is the very first line of the file. Then I suspect you'll find IE and Firefox will be more similar in what they are doing, and you can tweak the layout to get it the way you want.
Also, be sure to run your page through the HTML Validator, fix all markup errors, then do the same with the CSS Validator.
PS: If creating a new page, there is really no good reason to use a Transitional doctype. Use a Strict doctype and do things right, and reserve the Transitional one for legacy pages that you do not have the time and/or money to update to the 21st century.