The ISA Server 2004 beta is available for download from Microsoft.com. This is a good chance to take a look at the changes in the product. Here's the blurb from the page.
Microsoft Internet Security and Acceleration (ISA) Server 2004 is the advanced application layer firewall, VPN, and Web cache solution that enables customers to easily maximize existing IT investments by improving network security and performance. ISA Server 2004 Beta allows you to preview the upcoming functionality in this upcoming version.
You can also check out the new screen shots on the page. It's looking good.