I've asked the same question myself this morning, and the way I solved it was thru the HTML code. On the <body> tag insert this:
marginheight="0" marginwidth="0" topmargin="0" leftmargin="0"
rightmargin="0"

Seems confusing, but works. At least in explorer it does; don't know bout Netscape. If you have only one color in the background throughout job, you can forget what I've said till now and make the HTML
bgcolor(background color) the same as the movie.

Good luck, let me know how it works.