it's time to clean up my code and get a w3c validation.
in the original page i had

<div align="center"><IMG src="http://<mysite>/images/<image>" width="640" height="78"></div>

but w3c says 'there is no attribute "ALIGN"'
it mentions that i can get around this in the css.
i have been through a css reference and found nothing to center it.
how do i do this in my stylesheet?

<div style="text-align:center">
this validates ok :)

I think you need to put a space before the image if you wish to do this. another way of doing it is :

<div style="width: 640px; height: 78px; margin-left: auto; margin-right: auto;"><img src="http://<mysite>/images/<image>"/></div>

hope that helps.