No problem. In hindsight I might have overreacted or read something incorrectly.
So, anyway, all you need to do is understand what is happening and why.
You said something about a folder window popping up with the drive inserted that contains the Program Files and Windows folders. That is essentially the operating system files that are on the HDD that Windows puts there in order to work. You don't need to tamper with those.
All you need to do is boot from that HDD instead of from the HDD that is already in the machine. You can address any problems that arise after that.
So I'll work you through how to do that.
Since it's a Windows 8 machine, follow these steps to ensure that you are able to see the POST screen:
- Move the mouse cursor over to the top right-hand side of the Windows 8 desktop until the right-hand side ribbon appears.
- Click on the gear with the word Settings beneath it.
- In the screen that appears, click on Update and Recovery in the left-hand side pane.
- Select Recovery.
- Underneath Advanced start-up, click on the Restart now button. Your system will not restart yet, but Windows 8 will be stopped.
- The next option to select is Troubleshoot, from the options given.
- Advanced settings.
- UEFI Firmware Settings. Now, be ready. Depending on the computer it might only give you a split second to see the POST screen.
If there's an option to press a key such as F8 or F11, for example, to load the boot menu or boot from other devices menu, etc., then you want to press that key as many times as you can until the computer shows you a boot menu. Under this menu you may be presented with a few devices to boot from. Now, this may or may not work, but if at all available, select what ever device the USB HDD enclosure is identifying as using the arrow keys on the keyboard.
You'll just have to guess if you can't tell which one it is, but it most likely isn't an optical medium drive or the HDD that your Windows 8 OS is installed on which would be plugged in by SATA.
Alternatively, if you can't see any key to press, you will likely be brought to your UEFI/BIOS configuration screen for the computer. You can use this to navigate through to where the device boot priority is, and set the USB device to be the earliest choice. If that works according to plan, then after saving and restarting you will find yourself in the right situation.
Now it will attempt to boot from the drive. If you're lucky and the MBR is intact on the HDD inside the external enclosure then it will either blue screen prior to loading Windows 7 completely, or give you some other kind of error. From here on out you can either try this again but whilst hitting F8 after confirming that the computer is going to try to boot from the USB HDD. This will give you the Safe Mode screen and you can select any one of these to see if it will get you in with Safe Mode. If this doesn't work, then you'll need to give us any error messages and symptoms that the computer displays in full detail because it is going to be a rather painful process to get your Windows 7 up and running for a new piece of hardware.
Another thing you can try is a repair install on the Windows 7 device. You will just need to boot from a Windows 7 install DVD-ROM.
Here is an article explaining how to do that:
http://www.sevenforums.com/tutorials/3413-repair-install.html?ltr=R
Note that you'll lose your settings and possibly browser history, among other things. Your data should be intact. It will probably work on first attempt providing you can actually boot from the USB device.
And another article for if you'd like to configure Windows 8 to recognize that you have a Windows 7 installation on another HDD, otherwise known as dual-booting:
Dual Boot Installation - Windows 8 and Windows 7 or Vista
Then you can set it up to always give you an option which OS to boot in to when you start up the machine.
All written by our fair and awesome administrator Brink.
If you can't even get as far as booting from the USB HDD, in that the computer doesn't have the means or won't do it, then you might have to do some research on USB bootloaders or just remove the HDD from its external enclosure and put it directly in to the computer to get in to it. If you can't have both the Windows 7 and Windows 8 HDDs plugged in on the inside at the same time then you may have to buy another computer or settle for swapping them out. However, with a lot of painful tinkering you can get what you'd like to do working. But take this one step at a time for now.
There are other possible solutions but I am working under the assumption that you want to get in to your Windows 7 installation exactly as you remember it with all of your personal settings and others intact.
