How do I upgrade npm itself from 1.4.28 version to 2.1.14 on Windows 7?

After some struggling with upgrading npm itself from version 1.4.8 to 2.1.14 I ended up with following solution:

• I have installed NodeJS, newest version (just overwritten current installation)
• The npm was installed in (1) C:\Program Files\nodejs\node_modules\npm
• I have installed new version of npm: npm install npm -g the new version has been located in (2) %USERPROFILE%\AppData\Roaming\npm\node_modules\npm

Now, all you need is to delete all files in directory (1) and copy all files from directory (2) to (1).