In order to upgrade to Windows 8, you should check for hardware compatibility. Download the Windows 8.1 Upgrade Assistant by following this link.

After that, it's a simple matter of ordering Windows 8 from Cosoft. You would need to backup all your data, do a FRESH INSTALL of Windows 8 as advised by Microsoft here, and then do a brand new, full Aura installation. After that you need to restore your data and reconfigure all the devices and drivers on your installation.

Cosoft charges a regular Aura installation fee to perform the upgrades on your computers - as well as the cost of Windows 8.