Aerotower, just wonder why you have "Portmahomack" in your meta tags ;)
Here's the code I use to guarantee auto-update of the page and image. No idea how you refresh just the image without a page refresh.
<html>
<head>
<meta name="keywords" content="Portmahomack, Airnav, Radarbox, SBS1, SBS-1">
<meta http-equiv="refresh" content="60">
<meta http-equiv="expires" content="0">
<meta http-equiv="Pragma" content="no-cache">
<meta http-equiv="Cache-Control" content="no-store">
<meta http-equiv="Pragma-directive" content="no-cache">
<meta http-equiv="Cache-Directive" content="no-cache">
<body bgcolor="#000000">
<p align="center"><font color="#ff8000"></font></p>
<p align="center"><font color="#ff8000"><img hspace="0" src="http://www.tarbat.gofreeserve.com/shot/RadarBoxScreenShot.gif?<%=(new java.util.Date()).getTime()%>" align=center border=2></font></p><font color="#ff8000" >
<hr>
<p align="center"> </font><font color="#ff8000" size="4">This is a live feed from my Airnav Radarbox</font></p>
</body>
</html>