Yes, I have taken MSE off of the Vista machine after experiencing a total meltdown when the latest program update was available. It failed to install the update but in the process only partially uninstalled the earlier version and left it deactivated. I had to manually remove all remaining traces of the older version and then download and install the new one to regain protection from malware. After that, I found that the DB updates were failing half the time. The machine is now running Avast! 5 and it's more responsive, updates much more frequently, upgrades flawlessly, and scans much faster. MSE is the only Microsoft product I have ever been disappointed in but I can't recommend it at all.