We recommend that Windows Server 2008 be installed fresh and migrated to; or, just put new customers on new servers. We suggest that a well managed list of third party components and configurations is documented for each server, so that the current environment can be replicated on the new server. See the recommendations in the shared hosting paper for site and application pool configuration. A tool to assist in the migration will be released in the near future.
In-place upgrades are supported for the following scenarios:
Windows Server 2003 can be upgraded to WS2K8 Beta3, WS2K8 RC0, WS2K8 RC1, and WS2K8 RT
Windows Server 2008 Beta3 can be upgraded to WS2K8 Beta3, and WS2K8 RC0
Windows Server 2008 RC0 can be upgraded to WS2K8 RC0, WS2K8 RC1, and WS2K8 RTM
Windows Server 2008 RC1 can be upgraded to WS2K8 RC1, and WS2K8 RTM
If the server is in Shared Configuration mode, it must be reverted to standalone configuration before the upgrade is run. To do so, disable shared config, copy down the applicationhost.config and encrypted keys to the local machine, run the upgrade on each server, then re-enable shared config.