If you want to run multiple windows operating systems at the same time you first need a Windows computer, the installation disk for the operating system you want to run, and Windows Virtual PC 2007. To install this, first type in Virtual PC 2007 to Google, go to the Microsoft link and download and install the program. Now, open the Virtual PC and click next on the wizard. Name your hard disk and click next until you choose where you want this at. Now your virtual hard drive is created. Now, put the disk in the drive, select it and click start. Click CD tab and click use drive D and then go to Actions tab and click Ctrl+Alt+Del. Now, the screen will increase in size and you will come to the Windows vista. Select next on the screen and click Install now and agree tot he license terms. Next, select custom. Now, continue to click next and let Windows install. Now you can select your profile info like password and icon. Now select the hard drive in your new system and hit start and hit 'Start windows normally'. Now Vista should load with a log in page. Now here, run your setup and Vista and let this install and hit finish. You may need to restart the Virtual computer so the configurations take place. Now you are running Windows Vista while also Running Windows Vista - simultaneously.