I have 2 computers in my room. A laptop and a desktop. If I purchase Acronis True Image 2009, do I need to purchase 2 copies? If that is true, then if I purchased one copy, could I uninstall it from the first PC and use it to make a backup of the 2nd PC? If I can use it multiple PCs that I own in my house, is there a limit? Can I use it on my wife's PC?