The Web site header is the first thing people see when they come to your site.
Studies show that you have between 3 and 8 seconds to make your case that they should stick around a bit longer.
Unless it is immediately obvious what your site is about, you should consider a graphic header.
An appropriate header can communicate the core message of your site consciously (and subconsciously) within a split second.
You've spent a lot of time and money developing the content for your site. Give youself the advantage of the perfect header for your site.