Hi Jon
I am trying to accomplish the same thing without success. Yes, you can go the HTML way <IFRAME> or <OBJECT> but I believe the w3c HTML 4 spec says <IFRAME> is to be replaced with <OBJECT> and I have found that <OBJECT> doesn't always work in Netscape.
Right now I am trying to work it out with include("yourfile.inc"); with limited success.
Please let me know if you find an elegant solution to this problem...and of course there is one out there somewhere as we are working with PHP ;-)
Good Luck
Adam