Firstly, you will need to download VirtualBox. Once you have that installed, you will need to create a new XP Virtual Computer.
In the main window, press “New”. Then set the ‘Name’ to Windows XP or similar, and press next (usually the OS Type is set to XP by default, if it isn’t switch ‘Version’ to Windows XP.)
Set the Base memory to something above 512MB. I’d reccomend at least 1GB (this is your XP RAM).
Select ‘Boot Hard Disk (Primary Master)’ and choose ‘Create new hard disk’.
When creating the Hard Disk, select ‘Fixed-size storage’ because ‘Dynamically expanding storage’ will not work with an NTFS partition.
Now select how much space you would like XP to have. I’d reccomend at least something over 15GB.
Once that is done, click finish and VirtualBox will create the virtual machine.
When that finishes, insert your XP CD into your disk drive or mount it after ‘Start’-ing the machine.
Then simply install XP as if you were installing on a normal computer.
Once you have completely installed XP, and are at the desktop, press ‘Devices’ then ‘Install Guest Additions’.
When the installation finishes, reboot. After you get back to the desktop, either press Right Ctrl + L or go to ‘Machine’ and select ‘Seamless Mode’.
Congratulations! You now have XP running with Vista/7. Remember, you can also do this with any other Windows, Linux, or Mac Operating System.
If you’d like to go back to the default way, you can always press Right Ctrl + L. Enjoy! 🙂