How to upgrade xp to windows vista free?

There is no free upgrade from XP that I am aware of, however you can upgrade to Windows 7 by purchasing the software as a download or on DVD. I would suggest selling the new hard drive, plus an external hard drive area. Follow the manufacturer’s orders for installing the new hard drive in the external area, and then attach it to your computer via USB 2.0. Use free software to duplicate your drive, make an exact copy of your drive, OS, registry, etc, a total and correct copy of the entire drive, onto the external drive. You can now power off the computer, take away the old drive, install the new one and fire it up. All programs are still there, you might not even notice a disparity except the extra space. Now you can upgrade while retaining all of your files and programs, and still have a ton of space.