How to remove "This copy of windows is not genuine" error.

Steps of fix using Command Prompt:

1. Open Control Panel in your Windows from Start menu.
2. Click on System & Security. (If you are a Windows XP user, then there is no need to click on System & Security).
3. Click on Windows Update.
4. Click on View Installed updates. (See below screenshot for reference)
5. Now, look for KB971033 update. Right click on it.
6. Click on Uninstall.
7. It will show a popup. Simply, click on Yes.

Restart your computer and you will find that you have got rid of this error now.

What is difference between Program Files and Program Files(x86) folders in Windows 7 ?

The difference between the two is that "Program Files" is used to install softwares which are 64-bit softwares and "Program Files (x86)" is used to install softwares which are 32-bit softwares.

This is the default behavior. So if u find any softwares under "Program Files", remember they are 64-bit softwares and vice-versa.