I’ve been running the beta of Longhorn Server here for some time, and just this week I updated to the newly released Beta 3. I also downloaded Virtual Server 2005 R2 Enterprise Edition, which was released earlier this month.
But after installing the Virtual Server code, I encountered a frustrating error message when I tried to open the administration website. Instead of the famililar VS2005 web page, a dialog box appeared, telling me that it was trying to download VSWebApp.exe and asking me what program I wanted to use to run it.
It took me a while to discover the secret, which is that the default Longhorn installation didn’t install CGI support. Virtual Server’s administration tools rely on CGI extensively, as it turns out, so this is a serious omission. The fix is simple: Open Server Manager, expand the list of Roles in the left-hand tree pane, and select Web Server (IIS). Click Add Role Services, and then choose CGI under the Application development heading.
Finish installing this component and presto! You can now access the VS2005 web-based administration tools while logged on to the server.
If you want access to the admin website from a remote machine, you’ll need to tweak Windows Firewall on the server to open TCP port 1024 for incoming connections.
Ed Bott (@ wordpress.com) 
Great but can it be installed on the “Core” Install? This is where it would be must useful.
Chad, I’m not sure, honestly. VS2005 is administered via a web browser, so that would seem to suggest you need to have a web server running. IIS7 is the logical choice for that, but I think you can use Apache or something else if you prefer.
I won’t be able to test this scenario until next month. If anyone else tries it, leave a comment here.
Thank You for posting this.. It was driving me crazy.
m