If you ask me then there are numerous ways you can upgrade your Windows 7 any lower Edition to higher. In your Windows 7 install disk there are all Editions already present ,But you are only allowed to install only a particular Edition by default .
The process or method given below is of fresh installation :-
To remove this barrier you have to you have to copy your installation media on Computer and then go into "Sources" folder and then find this file "ei.cfg" and remember if you only want to change the Edition then open this file by Notepad and in the middle you will find a heading "Edition" under this heading you have to change your edition to your desired edition name .For example if your installation disk is of Home basic and you want to upgrade it to ultimate , then you have to change Home basic and write Ultimate below "Edition" heading into the "ei.cfg" file and save it , And if you want to create a Universal Windows 7 disk which contains all Editions then simply go to "Sources" folder placed inside the copied installation files and then delete that "ei.cfg" file from the "Sources" folder .
That's it this above explanation is about changing edition and creating universal Windows 7 disk.
Now,let's talk about upgrading the system .
Now boot your computer with the newly created modified installation media of windows 7 an select your desired Edition on which you want to upgrade your previous Edition (In case of universal disk example). remember if installation ask you about a product key then skip that option and complete whole process and then when your desired Edition will install then use a Windows 7 Activator by Daz and activate your system.
I hope this will help you out :)
Thanks for asking!