Hey,
I don't have time to go over your page too finely... but if you add a closing </table> to line 44 the site header moves up to the top. That table could have well closed itself later on, I don't have time to go through it. I ain't no HTML god, but I'm pretty sure your not suppose to wrap certain elements inside each-other (Frontpage first created a table within a <div>, than closed the div without closing the table). I'm aware it's not you making these decisions, or if you know what this means, but that was the first thing I found, and it seems to have done the trick.
If you can use a development environment, odds are you can do it by hand, and much better, it just takes time. I learned by watching the output of Claris Homepage and if you don't know anything about HTML just playing around at home with TextWrangler and Safari can teach you everything.
I know you might be forced into using FrontPage and just want a quick fix. So if your looking for that, the one above seems to do the trick.