I have been thinking of installing mulitple SolidWorks versions on my workstation.  Specifically 2010, 2011 and 2012 in order to support various customer requirements.

For years, I have avoided having multiple installations.  My preferences has been to completely wipe a previous installation and do a clean install of a new version.

Recently, I have been looking into using a virtual machine like Virtual Box.  For those of you who have mulitple installs, do you think it is even necessary to use this?  My goal is to be able to use multiple versions, possibly at the same time without having any cross-contamination of files.