Old HDD with OS will still work if I reinstall?

[Pacman4]

I removed my old WD C Blue as it was too slow, but I didn't reformat it, so all data including the OS{W7} is still on it, so if I were to remove my new HDD and put the other back in, is there any reason it won't boot up?

Or, could I simply add this HDD to my PC and have it recognized as a 2nd HDD?

 

[rasczak]

If it is going back into the original system it should. If the hardware is different however, ymmv.

 

[JackMDS]

The rule is one activation per one Lic.

I.e., if you did not used the Key of the Win 7 installation on another computer it will work and if the activation is not done auto., call MS activation support and they will activate it for you.

If you put it as a second drive it will be recognized as a Data drive and you can copy your files of it to the new drive or use it for other purposes, activation of a data drive is not an issue.

 

[Pacman4]

Ok Jack, I'll try and add it as a second drive.
I had the contents of it backed up on an external and it decided to die, the 2nd external that's died within a few months on me, one from Samsung and now Seagate.