EasyBCD is a program that allows to manage the boot of the operating system in case more than one is available. It allows you to easily modify the boot options in Windows 7 or Vista to determine whether you boot (start) first some alternative operating system such as older versions of Windows (XP, 2003, etc.) or other platforms such as Linux (Ubuntu), Mac OS X or NeoGrub.
It should be indicated on which partition is each operating system that you want to add to the list of potential candidates to boot. These can be found in external drives such as USB, or ISO images, VHD (Virtual Hardisk), network devices, and so on.
In addition to modifying and customizing the Windows 7 or Vista boot manager, EasyBCD makes it possible to back up the old ones, and restore old configurations. This application can be very useful also to repair damaged boot files.
EasyBCD allows you to create bootable drives on USB drives, USB drives or CDs, in order to boot the system from any of these external drives.
There is a complete video tutorial in Spanish, which explains in detail the steps that must be followed to use this program.
EasyBCD 2.2 is the latest version, updated in September 2012, of this dual boot manager that you can download free.