I Bought my mom and dad an iMac and need to install iWork. I have my copy that is installed on my computer. Can I use my copy of iWork to install and then just pay on line when the registration screen comes up or must I go to the Apple store and buy another copy? Also not too familiar with multiple user accounts. Setting up a user account for each of them on their computer. Do I have to install each program (like iWork) and any shared data files twice (once on each user account)? If so I hope they don't have to pay for a separate license to use on the same computer.