You may be playing with the new TFS 2010 Beta 2 bits. You may also be playing with MOSS 2007. And you may be doing it all on Windows Server 2008 R2 which is a rocking operating system. However, you may also be running into a small problem with the install guide (Microsoft is already aware of this and it’s being fixed for the RTM documentation). Once you install MOSS 2007 the install guide has you run two stsadm -o extendvs commands for SharePoint. However, they won’t work. The problem has nothing to do with the commands itself, but rather with how MOSS is installed. In IIS MOSS is installed under the DefaultAppPool but this app pool has the identity DefaultAppPoolIdentity rather than Network Service as it did in prior versions of Windows Server. To fix this problem, simplyy change the identity of the DefaultAppPool to Network Service and then run the extendvs commands!