I have sonar 8.5 running on vista 64, I set up a new user, downloaded, the trial, and tried to install it without messing up my current setup. It said it found the old version with shared links... deinstalling old version may require reinstalling plugins... 
It's not worth the risk to mess around with my current system now but I would like to test drive x2. I thought adding it under a new user would do it but no such luck. Any suggestions to get around deinstalling the old version. 

Installing it won't harm anything.

When you run our uninstallers, you will be prompted as to whether or not you would like to remove "Shared Components". You have the option to do this or not.

If you opt to remove them, then you're going to need to reinstall shared components since they're now missing.

If you opt NOT to remove them, then you're all set :)

I hope that helps!

Ryan: Surprised you didn't mention that Vista is not a supported operating system.

OP: When the next Sonar X2 update is available( very soon now ) you will not be able to install it on Windows Vista according to what has been communicated by CW.