One good thing about Vista’s DVD is that any DVD version could install another. For example a Home Premium DVD could install the Ultimate Version. A retail DVD could install a OEM version. What defined what could be installed was the actual Product Key.
So as long as you had a Ultimate Product Key you could use a Home Premium DVD should you lose your Ultimate. You could also use a retail Vista DVD and your OEM Product Key to do a nice vanilla install on your brand new crapware filled laptop.

This all changed with Windows 7. It seemed each DVD was different. That what it seemed like. But that’s not the case. There is a file called ei.cfg that controls which version is installed. Simply by deleting or renaming the file will remove the restriction and once again you will be given a choice of which version to install.

The file can be located inside the /sources/ folder. If you are installing from a USB stick this is dead easy to do however if you are installing from a DVD then you will need to re-create the DVD. The following guide will help you accomplish this.