Displaying Updated XML File

I'm trying to create an XML guestbook. I'm using a form for the user to input his name, e-mail, message etc. an .asp file to update the xml file and an .htm file with javascript to display the xml file. The .asp file contains a <meta> tag to redirect the user from the .asp file to the guestbook.htm file. Following the submission of the form the script in the .asp file runs fine and updates the xml file but the problem is that when the xml file is accessed by guestbook.htm in appears to be accesing a cached version. For it to display the latest entry i need to access the xml file directly (http://....../guestbook.xml), refresh it and then return to the .htm file.