As I wrote in another post you can access your Mac remotely, but if you want to control your Mac from a Windows system?

One immediate solution is to use vnc a famous software for the Microsoft world, Real vnc , this application allows you to add the VNC protocol to Windows systems.
Real vnc I suggest you download the free version, the software is also available for GNU / Linux.

During installation, you can choose the modules to be installed, by default installs the server and the viewer,
a choice that I advise you to be able to make more operations possible.

After installation you can use the Viewer going to call Run vnc Viewer from the Programs menu / RealVNC / vnc Viewer 4,
to connect you just enter the IP address of the server and, after pressing OK, you will need to identify themselves with a password of your choice.

With the program Real vnc Viewer, you can also change the connection options,
in fact if you press the Options before you connect you can have different formats in configurations where you can change the behavior of the vnc viewer.
If you want a good yield of the service I advise you to double check the setting of the maximum number of colors and the data compression algorithm.

More info at Real vnc Windows systems in the hands of Mac

(vnc stands for Virtual Network Computing) is a graphical system designed to access remote machines: protocol-based RFB (Remote Frame Buffer),
allows you to remotely control a machine. So, as guaranteed by the Remote Desktop feature of Microsoft Windows systems,
it is possible to act on a remote computer as if it were local, acting on your desktop (and managing the components)
through the use of mouse and keyboard.

The vnc system is based on two distinct components. On the one hand you have the server,
need to be installed on your computer that you want to take remote control,
the other a client (or viewer) to be installed on the machine from which you want to access (and control) and remote.
You must also remember that vnc uses TCP ports, with the standard configuration, ranging from 5900 to 5906 (corresponding to as many vnc remote screens).
The following steps illustrate how to establish a connection between a remote computer that uses Ubuntu 10.04 “Lucid Lynx”
(which will act as the viewer) and a remote machine (in this case, on a LAN) with Microsoft Windows XP SP2.

Read the full story here introduction vnc
More info at introduction vnc

We begin by clarifying that with vnc does not mean a particular program, but a category of programs that allow remote control of a computer.
The acronym stands for Virtual Network Computing vnc and the common feature is the use of such software RFB protocol, Remote Frame Buffer.
In this vnc article we use a vnc server on a Linux system on a Windows system. The information provided will be helpful, however, in any case configuration.

The scheme is simple: on the one hand to control the computer on which to install the vnc server,
the computer controlling the other hand using the client component, the so-called viewer.
The two machines can be connected via a private LAN or through the public Internet.
In the latter case the work is likely to be more burdensome for the need to configure other devices such as firewalls and routers. vnc

More info at vnc : how to manage servers remotely
More info at vnc : how to manage servers remotely