Different Windows Vista Purchase Options
Windows Vista can be purchased two main ways: upgrade or full retail. Before buying and installing Vista, and especially before running an upgrade installation, I recommend running the
Vista Upgrade Advisor.
Upgrade Version
An upgrade takes an eligible Microsoft product and upgrades it to Windows Vista leaving your files intact. However, if you view Microsoft's
Windows Vista End-User License Agreement (EULA) it states "UPGRADES. To use upgrade software, you must first be licensed for the software that is eligible for the upgrade. Upon upgrade, this agreement takes the place of the agreement for the software you upgraded from. After you upgrade, you may no longer use the software you upgraded from." This means that it will prevent you from using that Windows XP license in the future.
Full Retail Version
The full retail version can be installed as a clean install, which I stongly recommend. In this type of installation, you have to completely reformat your hard drive and install Windows Vista on the newly formatted hard drive. Since this will erase all of your data and settings, you should backup all of your important files. If you are buying a non-upgrade version you may choose to keep your current Operating System (OS) installed and shrink your existing
partition to create room for Windows Vista. That way, you can choose which OS to load when your computer is starting. If you would like to do this, but do not know how I would recommend joining a forum or asking a technically-oriented friend or relative.