Restoring a backup from external hard drive

I have a friend's computer that will not let me log on. That's not the issue. I want to back up his hard drive before reinstalling the OS. I plan on removing the hard drive and transferring the data onto an external hard drive and then once the reinstallation is complete, restore the data. The operating system is Windows Home Premium 32-bit.


It seems to me that a while back I had a similar scenario with another machine, also a Windows 7, but was unable to restore the backup data from off the external hard drive back to the computer. I never did find out why. So, I need to get the data off my friend's hard drive before reinstalling the OS but am concerned about not being able to restore that information.


Do I have to install some sort of restore app from Microsoft Windows in order to complete this back up and restore procedure? I could copy and paste, but holy cow—that would take an extreme amount of time!


Again, the steps are: 1. hooking his hard drive up to an adapter 2. locate his drive on my computer. 3. in the properties box of his hard drive click back up. 4. after reinstallation of OS, restore the data off my external hard drive back onto his hard drive.


I'm all ears.


Any advice would be helpful. Thanks