I think your page will be sorted for IE8 once you have proper a DOCTYPE declaration at the top of your html section of your page.
The DOCTYPE lines should look something like:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
You will need these at the top of each of your site's html.
Do you have the DOCTYPE declaration lines there already? There may be a problem with them (maybe unclosed tags). If in Doubt add new (or replace existing) lines with the above two.
Firefox/mozilla seems to manage without them, but IE needs to know what's expected of it.