How do I determine if an unbootable copy of Windows is a 64-bit or 32-bit installation?

I need to reinstall Windows on a laptop. I have the product key (its on the laptop), and I know it is Windows 7 Home Premium.

I need a way to determine if 64-bit or 32-bit Windows is installed, so that I can download the correct one from Microsoft. The computer is messed up so I do not have access to Windows to check it with systeminfo.

I took out the hard drive and hooked it to another computer, but when I run systeminfo it just gives information for the host computer, I did not see a way to change this.

Solution 1:

If you see a folder in the root of that drive named Program Files (x86) then it has 64-bit Windows installed.

Solution 2:

A slightly more accurate way of detecting 64-bit windows is to look for folder %SystemRoot%\SysWOW64 (commonly Windows\SysWOW64) since it contains the binaries windows uses to launch 32-bit applications it should not be present on 32-bit windows installations. This is a little more accurate than checking for Program Files (x86) because I recall seeing an installation option somewhere in Windows Vista which allows that folder to be renamed, but I've never seen one for SysWOW64.