The right way on changing your VirtualBox.xml location

There is often one recommended way to change the default VirtualBox.xml file location (C:\Documents and Settings\Username.VirtualBox) floating around the internet, and that is to use MKLINK (NTFS symbolic link) command. The correct way is actually found in the manual (Section 9.1), or basically: set the VBOX_USER_HOME environment variable to read from a location to your choice. Since it’s an environment variable, you may have to reboot for your computer to take effect.

That’s it. It’s as simple as that.