To get your content to touch the top of the page, rather than having a margin, put the following in the <body> tag (or use an external style sheet):
For netscape:
marginwidth=0 marginheight=0
For IE:
leftmargin=0 topmargin=0
And now with IE 6:
bottommargin=0 rightmargin=0
As usual, each browser remains stubborn so if you don't want any margins in either browser, you have to put them all in there.