I want to back up my WinXP, but I don't want to fill up my backup drive too quickly. When I was using Parallels 8 the "Optimize for Time Machine" feature did NOT work. Now I am using Parallels 10. When a Parallels tech helped me with a problem recently, I asked him about using SmartGuard and told him what I just typed in the first sentence of this post. Here's what he wrote in the chat window. " no don't enable samrtguard it will create snapshot often and increase the hard drive of windows ". So now I am really confused. The info from the Parallels web site says using SmartGuard will reduce the amount of space used in backups. The technician who works for Parallels and works with it all the time says is increases the space used in backups. What is correct? At present, in Security "Do not backup Virtual Machine" is unchecked. "Smartguard" is also unchecked.