Can I add a second HD with my old Win7 OS (different license) to new computer to transfer data?


New Member
Sorry for the long post, but wanted give all the background info.

I have been temporarily relocated for work. As part of the relocation, I had my desktop computer shipped out to me. However, in the process of shipping, the computer was destroyed by UPS. I'm still waiting for a check after 34 days...but that's another story.

Rather than wait for UPS to send me a check, I decided to build a replacement computer.
I wanted to use my original Win7 to do the install, but discovered the install disks are back home. It would take too long to get them and after reading some of the hassles required to get it to install on a different computer; I decided to get another version of Win7. I can always use the old Win7 OS once the dust settles with UPS.

So my question:
Can I temporarily install the old HD with the old Win7 OS on it in my new computer as a second HD so I can transfer the almost 1/2 TB of info to my new HD?
Will the OS's conflict? I'm paranoid about messing up my new build.
I've done some searching and most forums and Microsoft tips deal with transferring data from a working computer - I don't have that.

Couple points:
**I assume if I get a SATA USB HD enclosure, it may conflict the same as the HD installed as a second HD.
**I'm out here a fair distance from any computer store so running out and getting something is a hassle.
**The new OS is the same type as the old computer, Win7 64 Pro and all the hardware is almost identical. All SATA drives.
**I have two Win7 licenses.
**I have very limited computer resources. Everything is on my old HD.
**New computer only has the Win7 OS on it and drivers for MOBO, etc. It runs perfectly.
**Again, old computer is destroyed and cannot be operated. All I have is the HD.

Any suggestions?

Hello MnM3,
to Windows 7 Forums,

You shouldn't have an issue adding the old drive.
My 1st suggestion would be to, disconnect the new drive, connect the old drive and fire up the PC to see if it boots up to Windows, if it does, shut down, re-connect the new drive (leaving the old still connected) and turn on the PC, it should boot to one or the other, next download and install EasyBCD and add the OS that's not indicated by EasyBCD, (very easy to use tool, hence the name) and choose which one you want as default, you should now be in a dual boot setup, you will have a choice of which Windows to boot to during the boot process.
If the drive does not boot, shut down and re-connect the new drive, again, leaving the old connected and turn on the PC, you should then be able to access the drive from within the new Windows.

Hope this helps


Extraordinary Member
Premium Supporter
Although there may be a collision between the two OS, it can't be fatal because they are both licensed properly. I agree with Don but, personally I would keep the new installation and work from there, and then only pick the data I want from the old disk. You can copy the whole disk to the new one. But that's pretty much a matter of personal taste. JUST BE SURE not to allow formation of your old disk... sometimes things happen by accident... :(

There is also a thing called Parallel Installation, How To Install Windows 7. Never used it, but it might be of interest to you. More can be found with a Google or other search "parallel install windows 7".

Best of luck. :)

Last edited:


Excellent Member
Microsoft Community Contributor
The system will boot to the first active partition it comes to during boot. If the new drive is set to primary in the bios, it will boot to that. Plugging or unplugging drives can change the drive order in the bios, so be careful. If you were to boot, or try booting to the old drive without the new drive present, it would become primary even if you reinstall the new drive later.

Moving an install (old drive) to a new system, as you mention, can present problems. I have moved and XP and Vista install and they worked fine, but there are no guarantees. If you do move the drive and use it in a dual boot scenario, if it does boot, you will probably need to call Microsoft (automated) and give and get some numbers from them and confirm the install is only on one system.

If you decide, and are able, to use both installs, the EasyBCD suggestion is good, or use the Bootrec /ScanOS command from the recovery environment to add the second OS.

Edit: I am assuming the old hard drive does not contain an OEM install. If it does, you probably will not be able to move it.


New Member
Thanks for the words of wisdom, but it appears as though - "Houston; we have a problem."

I forgot to (look and) mention that both Win7 OSs are OEM. Grrrr.

I assume I'm out of luck when I try to add the old HD to the new system as it will be looking for the old MOBO.
Is that a correct assumption? Or by some miracle, will booting to the new HD allow the old HD to assume the role of a slave HD?

Option 2: Can a USB drive enclosure be used? I have assumed all along it will act the same as an internal install due to the conflicting OS or OEM MOBO specific requirement.

Not looking good right now.

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