Upgrading an IIS Server to IIS 6.0
You can move Web sites and applications to Internet Information Services (IIS) 6.0 in two ways. Upgrading is installing the Microsoft® Windows® Server 2003 operating system and IIS 6.0 on an existing server running the Windows NT® Server 4.0 operating system and IIS 4.0 or the Windows® 2000 Server operating system and IIS 5.0. Migrating, on the other hand, is installing Windows Server 2003 and IIS 6.0 on a new server and then moving, or reinstalling, existing Web sites and applications to that server. Both processes involve minimal outage of service to users that access the Web sites and applications, while retaining the majority of the original configuration settings and fully preserving the content of the Web sites and applications.