When you try to upgrade your existing computer from Windows XP to Windows Vista or when you perform a clean install on a new system, then the process of installing Windows Vista is pretty straightforward.
It will definitely perform a clean install which means any files that are on your machine, as part of a previous operating system, will be removed. This also means that you should take a backup of each and every data that you wish to keep before performing a clean install in Windows Vista.
BEFORE INSTALLING
Always remember that before you install any operating system on your Windows Vista computer, it is extremely important to make sure that your system is compatible with the type of OS that you are installing. But make sure that your hard drive, RAM memory, and processor speed are at least the minimum required for the OS to work properly. You can accomplish this if you are using Window's Vista by visiting Microsoft's website or consulting the documentation that came with your CD or DVD copy of your Windows Vista.
PRE-INSTALL
If you want to upgrade from those previous versions of Windows, you can simply insert your Windows Vista disk into your computers drive. After this the process will start by itsself after a moment or two however if the program fails to launch by its self you can force it to begin by going to START>RUN option and then type in your drive letter followed by: setup.exe and then press OK.
This step will definitely start the process and you should see a screen that gives you the option to install. Just go ahead and click ok to start the install.
INSTALLING WINDOW'S
Now you just have to install again if you are performing an upgrade you should be able to select upgrade when the