If you've downloaded the RTM version of Windows 7 and for some reason DONT want the Ultimate edition, there's an easy way to choose upon installation.
Once you open up the ISO image, you have two choices:
a) Delete iso://sources/ei.cfg (Easiest)
Save and burn the image. When the installer runs, it will ask you which version you wish to install.
Now you're done :)
b) Modify iso://sources/ei.cfg to set the default (Harder)
This will change the default installation and will not prompt you what version you wish to install.
Extract ei.cfg to a temporary location and edit it with Notepad. The default values for ei.cfg are:
Change the values to any of the possible values:
"Ultimate", "Professional", "HomePremium", "HomeBasic" or "Starter".
"Retail" or "OEM"
- VL (Volume License)
"1" (true) or "0" (false)
Once thats done, update the image and burn it.
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