Okay, I have to do this to my wife's laptop. Here is what I'm planning to do. First, I will buy a new hard drive, and I'm leaning toward a SSD drive as a replacement. I'll put the replacement drive into a USB external unit and then boot into Windows and use a mirroring drive software to mirror the old drive to the new drive. After that, I will remove the old drive, and put in the new SSD drive, and it should come up just like the old drive, same programs installed, icons on your desktop, everything. The mirroring software is sometimes on your new drive. If not, you'll need a good mirroring software to do that. There are several out there, and probably some free ones too, but I've not had a lot of experience doing this so I'm not sure what is superior and what is not. After that works, I will put the old drive into the USB external unit and plug that into the computer, and re-format the drive using Windows.
You really shouldn't need Best Buy or whoever to put the drive into the external unit. You should see the SATA plug, and the power plug. You can't mix them up. Plug them into their respective interfaces and voila - thats pretty much it.
If mirroring is out, in other words if the old hard drive's registry is truly whacked and can't be saved, then you'll need to install fresh Windows on your new hard drive, then bring up the old hard drive in the USB external case and copy over what you want. Any programs, you'll need to re-install but you should be able to copy your data files over, then re-format the old drive using Windows whenever you want.