The common files location is being set in the PSF files. I've had no issue (so far) altering the common files location to one of my choosing. I typically install on a PC, copy the install folder to a server, re-organize the folder structure to my liking, then update all files accordingly. I use a text editor (Notepad++) that allows me to find and replace all occurrences of a text string in all files in a directory (or set of directories). This makes it very easy to replace install paths from something like "C:\PTC\Creo_2_F000\Creo 2.0" to "H:\Creo 2.0". For our users here, we only run Proe/Creo from the network. We never install locally (except on laptops). This makes administration MUCH simpler. I also use a homemade batch file to launch Proe/Creo. This allows me to setup the necessary environment variables at run time instead of hard configuring them on each computer. Across the board we use one version. When I decide to roll out a new version, I simply change one line in my batch file and the next time everyone starts up, they will automatically be running the new build. For maintenance releases, no one ever even knows they've changed builds. For major releases, it's a more obvious, but still requires no work from the end users (other than dynamic installations like thumbnail viewer, etc.).
Tom U.