One of the cool things about Windows Vista is that, if you have an installation DVD for Vista Home Basic, Home Premium, Business, or Ultimate, you can use it to install any of those editions — which one you get just depends on which product key you enter at the beginning of the installation. For some reason, Microsoft took this cool tidbit away from Windows 7. The disc you get only lets you install one edition.
However, there’s an easy way to turn such a “locked” disc into a disc that will install any edition again, just like with Windows Vista.
First, make an ISO image of your Windows 7 DVD if you do not already have one. (I use UltraISO, but there are any number of utilities for doing this.)
Then, open the ISO image in your favorite ISO editor (again, I use UltraISO). Navigate to the “sources” directory and delete the “ei.cfg” file.
Save the image and burn it to disc. Now, when you use it to start a Windows 7 install, you will get the option to choose which edition you want to install.
Make sure that you choose the one that matches which version you actually have a license for! Otherwise, you will not be able to enter your product key at the end of the installation process.
Note that Windows 7 Enterprise is not included in the list in the screen shot. Like Windows Vista Enterprise, you’ll need a separate disc for it still. However, if you are using a 32-bit Windows 7 install DVD, you will also have “Windows 7 Starter” on the disc.
Update: October 11, 2012
I’ve noticed that this method kills the UEFI bootability of the Windows 7 disc. UltraISO must not be UEFI-aware and does not write some necessary boot information when the image is saved. Other utilities may properly preserve the UEFI boot information. Anyway, to get around this, use BennyS’s method from the comments below: Just open the image in a hex editor and rename the ei.cfg file to something like ei.xxx.