How to: upgrade from previous versions of Windows using Windows 10 ISO file
Technical Level : Basic
As we approach the launch of Windows 10 this summer, hundreds of millions of existing Windows users will be taking advantage the opportunity to upgrade their current version to Windows 10 for free. This represents an unprecedented change in Microsoft's business model of requiring purchase of a license. Windows 10 will be offered two ways to existing Windows 7 and Windows 8/8.1 users. You will be able to download the update through Windows Update or you can download .ISO media and use it do an in place upgrade. For many persons, using ISO media will be the preferred method since you will have a backup copy for reinstall purposes if needed. Also for persons with limited bandwidth, this will be an excellent way avoid the need to download the update more than once if you have multiple computers. So lets take a look at upgrading to Windows 10.
I just read this in the MS Community
Gary, Your making this so complicated. You enter your key for Win7/Win8.1 and MS will verify it.. this is not an activation process. You can't just enter any numbers.. it's got to be a valid MS licensee/key. Stop worrying.. this is not going to be that complex to get the upgrade to Win10.