It is not mandatory to use utilities like RealVNC to take control of a remote Windows machine. Microsoft includes an inbuilt protocol for taking high-performance remote access called RDP. Here is a small guide for "Remote Desktop" of Pro and Ultimate editions of Windows Vista and Windows 7!
Since Windows 2000, Microsoft has ensured that a home user can take remote control of your PC remained in the office. Only the Professional Edition and Ultimate (Ultimate) of Windows can be taken into control.
However, any Windows (versions including Starter, Home Basic) can be then used to take control of the remote machine. We can even do this from a Mac since Microsoft has also developed a RDP client for MacOSX.
Let's see how to use the remote control of Windows 7 "Ultimate RC" so you can control your PC from any computer connected to the Internet.
Obviously, to take control of a machine via the Internet, it must be able to find this machine and designate through the canvas. For this, we invite you to read and practice the trick: How to access the computer running Windows 7 without fixed IP