It has come light that testing the Windows 8.1 preview will not be as straightforward and will involve some prerequisites.
Do not install it on a production machine or boot drive.
Microsoft Senior Product Marketing Manager Michael Niehaus reiterated that message in the RT in the Enterprise session on Tuesday. When the 8.1 preview is available, Windows 8 and Windows RT users will receive a Windows Update notification. That update will trigger the new bits to show up in the Windows Store, where potential testers will be able to read the description and choose whether or not to install.
Once the final versions of Windows 8.1 are available, after their release to manufacturing, those who have downloaded the preview will get the same Windows Update plus Windows Store notification. While their data and accounts will be preserved if and when they choose to install the free, final 8.1 release, all their apps must be reinstalled, Niehaus said.
Even if testers opt instead to roll their devices back to Windows 8 after installing the preview bits, they still will have to reinstall their apps once they move to the RTM version of Windows 8.1.
Windows 8 users who do not install the preview build and opt instead to go straight from Windows 8/Windows RT to Windows 8.1 will not have to reinstall their apps. All settings, data and apps will carry over, a spokesperson said when I asked. Users will be able to decide when and if they want to move from Windows 8 and Windows RT to the 8.1 versions, officials stressed.
Source:
http://news.cnet.com/8301-10805_3-57587794-75/how-windows-8.1-upgrades-will-get-to-you/
How to prepare:
Backup your system before:
http://www.notebooks.com/2009/10/24/how-to-backup-your-installation-of-windows-7/
Check out the following article by Microsoft MVP JW Stuart about how to backup a Windows XP installation here using Acronis True Image here
Another solution you can use for backing up Windows XP is Easeus To Do Backup, JW Stuart also has an article about it here
These same principles should work for persons running Windows Vista.
If you are running editions such as Windows Vista Business, Enterprise or Ultimate editions, you can use the built in Complete PC Backup of your Vista installation. This can be very handy in case your Windows 8 installation fails. For instructions about how to use Complete PC Backup, see the following article here. Of course, you will need an external hard disk for this task.
Create a partition:
http://notebooks.com/2011/02/25/how-to-create-a-simple-partition-in-windows-7-quick-tip/
Dual boot:
See instructions for dual booting based on installing the Windows 8 Previews, same principles will work for the Windows 8.1 preview:
How to dual boot Windows XP and Windows 8
How to dual boot Windows Vista/7 and Windows 8
Use Virtual Machine software:
This is recommended if you have a powerful enough processor and lots of memory.
You can use alternatives such as Oracle VirtualBox or VMWare Player.
https://www.virtualbox.org/wiki/Downloads
VMware Player;
http://downloads.vmware.com/d/details/player_401/dGpkYnRwd3didGRwQA==
If you are running Windows 8 Pro on a computer with SLAT support Second Layer Address Translation, you can use the built in Hyper-V that comes with Windows 8 Pro edition.
Will update this article with relevant content.