Our sys admins love XP because they could tailor an installation for any client company completely, and then Users could add-on their own customizations easily without affecting the Base Install. So, administration of those User PCs allowed mass admin updates, changes, etc, plus allowed Users to always have their preferences comfortably and productively available.
Win7 changed some of that. Customization was more restricted but with additional training, most users were able to re-locate their comfortable productivity (except for the awful downgrades inside WinExplorer).
Win8 is changing all of that. It can be a canned environment with few User Level customizations for their individual productivity, or it can be all customizable. Almost no middle-ground. Users either do everything the same way all the time (yeah, riiiight) or Administrators may spend hours on every User PC to effect any mass change.
I think this will be the bigger issue as Win8 plops onto corporate settings. No admin is going to worry about “Where’s the Start button” but “Where’s ANYTHING?!! This user has turned all those features off so he can be productive!”
Even Corp MS has issues with this.