Look at this website http://www.ajclassifieds.net/products/forsale/demos.php theheader graphic changes, what is the best way to do this for a website? Is it just a animated gif?

The logo changes???

There's a whopping great annoying Flash banner that takes up half the page is that what you mean?










<aside> Please say no

<!-- TOP SPOTLIGHT -->
<div id="ja-topsl" class="wrap">
<div class="main">
<div class="inner clearfix">
<embed width="960" height="250" type="application/x-shockwave-flash" pluginspage="http://www.macromedia.com/go/getflashplayer" wmode="transparent" quality="high" src="/images/ajclassified_header.swf"/>

There's your answer, Flash, coding from the webpage you submitted.

The image in that link is flash, but you could make a gif image to do the same thing but that is a pretty big picture, i would forget about it and fill that space with content instead.

This is super easy to do, look me up. I can get this done for you in an hour. Just supply the pictures you want faded in and out.