For Windows, we are going to use msysgit available at http://code.google.com/p/msysgit/downloads/list.
Download the most recent version of the full installer for the official Git, currently
Git-1.7.6-preview20110708.exe, and then double-click on the downloaded file link to begin the installation process.
Click on Next, and then click Next again on the GNU General Public License screen.
On the Select Destination Location screen, click on Next to accept the default destination.
On the Select Components screen, accept the defaults again, and click on Next.
On the Adjusting your PATH Environment screen, select Run Git and included Unix tools from the Windows Command Prompt as this will allow Git to work with Drush, which we will cover next.
You have installed the Git version control system—a tool that will greatly facilitate interaction with the existing contributed code at Drupal.org.