Preparing for the Installation

• Before you install Windows XP alongside Windows Vista, make room on your hard drive for the operating system. The easiest way to do this is to put a second hard drive into your computer and install XP to that hard drive. However, if you want to install it to the drive Vista is already on, you'll need to use partition management software, like the free, open-source software GParted, or the commercial software Partition Magic, to resize your current partition to make room for another one. You may also want to back up your current Vista operating system and save any files or data to an external location. While dual-booting is not an inherently dangerous task, it does involve a major change to your computer, so it's prudent to back up any important information before making any system changes. If you have the most recent Vista service pack, you can also use Vista's own Disk Management system to shrink a partition.
  
  

Installing the Operating System

• Insert your XP disc into your computer, reboot the machine and use the boot menu to boot from the CD. Once you enter the setup menu, choose the option to install XP and then look for the partitioned space you created earlier (either in a separate partition or separate physical drive partition). You'll need to select this partition as the one to install XP to before continuing. The actual installation process will take anywhere from 30 to 60 minutes, depending on the speed of your computer. Enter in the license key for your Windows XP operating system along with the current date, time and time zone. Once the installation process is finished and the computer reboots, finish the XP installation and get your Windows Vista Installation disc ready to repair the boot menu.
  
  

Repairing the Boot Menu

• The Windows XP boot menu doesn't recognize Windows Vista. You can fix this by inserting your Windows Vista installation disc and selecting the "Repair your computer" option. Select Windows Vista as the operating system to repair. Be aware that Windows XP won't be available in this option since the Vista installer won't see it. Click the "Command Prompt" option. Type "Bootrec.exe /fixMBR" and press "Enter." When the command finishes running, type "Bootrec.exe /fixBoot" and press "Enter." Close the window and restart Windows Vista. A boot menu will appear with both versions of Windows as options.