As Lukasz mentioned, it's very possible to have multiple versions installed at the same time. There are several very important things you want to do to make sure they all stay separated from each other:
- Use a different startup (working) directory for each one. This is set by the "start in" location on the shortcut you use to launch the program.
- If working with Windchill, set the PTC_WF_ROOT to a unique location for each one. This is easiest to set at the end of the PSF file located in the \bin folder for each installation. (If you have multiple license configurations then you need to add this line to each one.)
- For Creo Parametric, set the config.pro option "load_ui_customization_run_dir" to "yes". This tells Creo to look in the working directory for the config.pro file instead of somewhere buried in the user's profile.
- It also can be helpful to set "startup_check_for_visualization" to "no" if you don't want to be prompted about each version of Creo View Express.
First, congratulations on giving it a try, Antonius 
As for your questions Tom answered all of them, I'd just add one thing regarding UI customizations.
As you know, with Creo PTC decided to ditch config.win as a way of keeping UI customizations and introduced file creo_APPNAME_customization.ui (so it's like creo_parametric_customization.ui). And they keep this file by default in profile directory, the same you can set with PTC_WF_ROOT variable. That way you can keep separate UI customizations for different versions of Creo even when you're not using Windchill.
I see it this way: if you're not working with Windchill and want to keep separate UI customizations for different releases of Creo (eg. Creo 2.0 and 3.0), setting PTC_WF_ROOT will keep them that way. If you want to have different UI customizations for different projects made with the same release (like Creo 3.0), config option Tom mentioned comes in handy. Of course you can always use load_ui_customization_run_dir without ever setting PTC_WF_ROOT and it will also work.
Actually I ended up recently with modyfing psf files in our classrom by adding PTC_WF_ROOT for every release of Creo and ProE just to be sure they won't share any UI customizations or Common Folders additions.
Not exactly. I fiddled a bit with a batch script for unattended installation of Creo and ProE (using WPKG software) and at the end of installation script I simply echo ENV=PTC_WF_ROOT=<folder_path> and append it to psf file created during installation. I have already created appropriate profile folders on training machines, so the variable points to existing folder with settings just for Creo release script is installing at the time. The idea was to have separate environments for every Creo/ProE app and have it configured with minimal user (my) input 
Antonius Dirriwachter wrote:
Interesting. Does that mean you change the environment variable PTC_WF_ROOT in a batch file appropriate for the session you are going to run?
Yes, absolutely! This is exactly how I setup the environments for our users. Anything in the PSF file can be set as an environment variable instead. For license selection, instead of making a bunch of different PSF files, I comment out the feature line in the PSF file and instead set it with a batch script. I also set things like working directory and PTC_WF_ROOT location. I set these differently depending on whether the user is connecting to our production or development Windchill system, what version of Creo they want to use, whether or not they want debugging turned on, or if they simply want a clean virgin session to troubleshoot in.
If you launch Creo with the executable (parametric.exe), it will automatically read in the settings from parametric.psf. If you have multiple psf files in the folder, it will instead prompt you to choose your license configuration. Whichever one you choose will then be read in.
If instead you launch Creo from the bat files, the bat file will list what psf file to read in. Environment variables can easily be set prior to this line.
Assuming you want to set the PTC_WF_ROOT location, you can do this many different ways:
- Create a new environment variable on the computer.
- Set the environment variable in the batch file (assuming you are launching via bat)
- Set the environment variable in the PSF file
Since I'm just getting ready to roll Creo 3 out I decided to double check where files are being stored. Here is a matrix showing the behavior:
Is there is particular reason for this?
As Lukasz mentioned, it's very possible to have multiple versions installed at the same time. There are several very important things you want to do to make sure they all stay separated from each other:
- Use a different startup (working) directory for each one. This is set by the "start in" location on the shortcut you use to launch the program.
I have just installed Creo 3 with Creo 2 still installed but would like to keep both versions starting into a same directory? What could it caused?
