Your link loads in IE7 and Firefox but nothing shows, just a white screen.
Font sizes often are different in Firefox and IE, for normal text and headings; also the top and bottom margins for <h> and <p> tags are different so it's usual to specify exact sizes in px to get the looking the same.
If you use relative sizes like medium or small or use ems or say nothing then browsers will show slightly differently.
I don't use Dreamweaver but there must be a setting to size font and margins, or edit them in yourself into a stylesheet or within <style>...</style> tags in the head section :
body { font-size: 16px; }
h1 { font-size: 20px; }
p { margin-top: 5px; }
h1 { margin-top: 8px; }