IE and CSS

Okay, so I'm finally getting around to working on the website for my web design business. The only problem is, what works in Mozilla Firefox (FF, my browser on this computer) won't work in Internet Explorer (IE). Here's a snippet of code I'm having a ton of trouble with:

#header {
margin-left: 235px;
margin-right: 235px;
padding: 10px;
height: 100px;
width: 700px;
}
#left {
position: absolute;
left: 235px;
top: 160px;
width: 200px;
}
#center {
top: g0;
margin-left: 440px;
margin-right: 235px;
}

For those of you that can't tell, that's a part of my stylesheet. In the header div layer, this works absolutely fine in FF. However, when I try this on IE, my center div layer scoots down about 30-40 pixels. My left div doesn't seem to have this problem. I've already tried changing the 'top' attribute in the center div, but then it reverses the problem: it will work in IE, but not FF.

I never, ever, had this issue while designing the website for Homeland Title. Everything worked fine on that one.

If you have any ideas as to what the problem is, or if you have a possible solution, please comment or email me. Thanks in advance!