use CSS like he say or...
put the banner in a table by itself, then put your main table below it. You can have more than one table on a page. I do this a lot since I usually build my sites header graphic and navigation buttons in one table and the main content in a table below it. With no space between, they seem as one. That way I can copy and paste my header/navigation to a new page. Anyhow, try that. Just make sure to hit return a few times if you need more space. The CSS is probably the best way overall, a bit less work and CSS is pretty much standard across browsers now I think.