Looking good, check out http://blogs.msdn.com/mikekol/archive/2006/07/25/676977.aspx for the link to the latest VPC Additions!!
PS, if you want to set up Virtual Server 2005 R2 on Vista then check out http://blogs.msdn.com/virtual_pc_guy/archive/2006/06/05/618547.aspx.
I personally ended up doing the manual install of the IIS 7 components, which in itself was interesting as I discovered where all the install pieces for Dev are on IIS7. Anyway your mileage may vary and the script install may work for you.
Once installed the thing to remember is to start IE using "Run as Administrator" and then link to the Virtual Server admin site... If you don’t do this your admin credentials don’t get passed to VS Admin and you'll not be able to administer your virtual machines.
It works well!!