How do I install Snow Leopard while keeping files, applications, and settings

Question

I need to update my system, I realized that I need Snow Leopard (quiet late) before Maverick. My question is, how can I install it keeping files and all the data. I found this on Internet, does it work?
Install Snow Leopard while keeping files, applications, and settings
If you follow these steps, the installer will replace your operating system if one is already present, but will preserve your account information and personal files.  You may have to reinstall some applications, however.
Insert the install disc (or the first install disc if you have more than one) into your disc drive. Restart your computer while holding down the c key. This causes your computer to start up from the install disc rather than your hard drive. When you see the gray Apple insignia, release c . 
The Mac OS X installer should open automatically. Follow the on-screen prompts to read and accept the license agreement and begin the installation. When prompted to choose a destination disk, select your preferred location and click Install. 
When the Mac OS X installation finishes with the disc, restart your computer. After the installation completes, a configuration program may begin automatically if you are installing for the first time. You will need to supply basic setup information for your computer. 
Update your system software to ensure that you have the most recent operating system components.  From the Apple menu, select Software Update... , and then follow the instructions on the screen. Often, you will have to restart your computer, and you may have to run Software Update multiple times before it can completely update your system.

Answer 1

That's why you need to back it up. You won't need to restore the backup immediately afterwards unless something goes wrong during the upgrade, but you'll need it later; the drive will eventually fail.
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