Use padding-bottom instead:
h2 {
font-family: Georgia, "Times New Roman", Times, serif;
font-size: 16px;
font-weight: bold;
color: #000000;
padding-bottom: 25px;
border-bottom: 1px solid #cc0033;
}
My test in IE8 showed the line moved down. I think this is because the red line is the border-bottom for h2, so margin-bottom will add space below the line, which you won't see.
Learning this stuff myself, so happy to be shown if I'm wrong.