Hi John, I can't give you a definite answer but I have 03,04,05 eDrawings (not pro) on my pc for SW03,04,05 and it is ok. There will probably find another entry in your SW addins for 06 after you install. I have the 3. You just need to make sure to check the 05 version only when you make edwgs from SW05.Here is a quote from the release notes.HTH. neil Installing Multiple versions of eDrawings.
a.. For SolidWorks : The eDrawings version corresponding to the SolidWorks version should be installed to use the Publish or Animate functionality in SolidWorks. For example, eDrawings 2005 should be installed for integrating with SolidWorks 2005. Other versions of eDrawings installed on the same machine are not integrated with SolidWorks. However, you can continue to use those versions as standalone installations and the Save As
*.eprt/*.easm/*.edrw functionality in SolidWorks is still available.