Win 8.1 Disk or ISO (Already Have Product key)

I am seriously considering a Microsoft Surface Pro 3. Unfortunately it comes only with W8.1 so I will probably do a clean install with a version of W7 I have left in a three pack (Please - no response on how good W8.1 really is). However, I want to retain the option of reinstalling 8.1 on it in the future but the Surface does not come with disks. I will obviously have a legal 8.1 Product Key so where can I get the an 8.1 disk or ISO without having to buy an entire new version with a different Product key?

Thanks !!

Well, it turns out to be a moot concern. I found out W7 cannot be installed on the Surface Pro so reinstalling W8 will not matter. I immediately installed Classic Shell. It does not give it a full W7 experience but it is close enough.

Thanks again for the help above.

You warned people not to try to suggest a solution while keeping Windows 8 so we didn't post about that.

Classic Shell should make the user interface indistinguishable. There is zero reason to install Windows 7 for UI reasons, since Classic Shell can make Win8 identical to Win7 UI-wise.

Can you post what's missing?

Here's how to disable annoying Charms:





Here's an identical Windows 7 Start Button if you don't have one, for example:



Save the button file to computer then browse to it:

Of course you can't run Win 7 on a Surface Tablet. MS never intended anything but 8/8.1 to be run on them.