How can I demo version 7 without losing my 6 install? once the VM's are migrated to 7, can I remigrated them back to 6?
I don't think that 6 and 7 can co-exist. I would: back up the VM uninstall PD 6 install PD 7, this will update your VM (in particular the VM specific tools and drivers) play with it and see how you like it If you don't, uninstall the PD 7 tools from the VM (using Windows' uninstall feature), shut the VM down, and then uninstall PD 7 (but keep your VM files!). Re-install PD 6, open the VM, and install the PD6 tools. If all fails you'll still have the PD 6 backup.
Installing version 7 removes version 6. On first boot of Windows Parallels updates Parallels Tools. If you decide to revert to version 6 again then remove Parallels Tools, shut down Windows. Remove Parallels 7 and reinstall version 6. On first boot it will install Parallels 6's version of Parallels Tools. Even though this has worked flawlessly for others I would backup anything important on the VM prior - just in case.
