When you plug in the Arduino, you may hear a sound from the computer and a little popup bubble in the bottom right corner of the screen that says Found New Hardware FT232R USB UART

After a few seconds, the new hardware wizard will start. Select "No not this time" and click Next>

At the next screen, select Install from a list or specific location

At the next screen make sure Include this location is selected and browse to the folder that contains the driver you downloaded. Select the folder and click OK

It should copy some files and then come up with this window. Click Finish

Almost immediately, another window will pop up, this time it will say USB Serial Port. As before, click Install from a list or specific location

Browse to the same folder again...

And it should complete successfully!

You may need to reboot the computer.

When the computer is done rebooting, make sure the Arduino is plugged in (and the green light is lit). Go to the Device Manager (From the Start Menu, select Settings->Control Panel. Double click on System and select the Hardware tab. Then click on the Device Manager button)

Look for an entry under Ports (COM & LPT) that says USB Serial Port (COM) the COM number may vary but it should be something like COM3 or COM4. The COM stands for "communication", and each one has a unique number, known as the COM Port number. In this case the COM Port number is COM3.

If you don't see the COM port verify the Arduino is plugged in, and check that you installed the VCP FTDI driver.