To go from SambaPOS3 to 4 follow the instructions on the Download page that say:
For the Windows upgrade there really is not a step by step you simply put the disk in and follow the prompts Microsoft provides.
I would like to add if you purchase a NON OEM Retail licensed copy of Windows 7 then you can get Windows 10 for free when it comes out if you go to
And sign up. This deal is only running for a year so it will disappear I recommend you sign up as soon as you purchase windows 7.