Local Install of 2004 and Network License of 2006

From my IT guy:
"Well, I have some bad news... I don't think I can have both SW '06and SW '04 on the same machine. Today when I tried to start SW '04,I got an error and then discovered that it was trying to launch theSW '06 executable."

I know it's possible to have them both, but how? If we install 2004then 2006, do we need to change some registry setting orsomething?SolidworksAdministration