You can't. Remote Desktop is a proprietary Microsoft technology that only works with Windows systems. You can view a Windows desktop from a Windows machine, and you can also view a Windows desktop from a Mac OS X machine (with Microsoft's Remote Desktop Client for Mac)... but you can't view a Mac OS X desktop from a Windows machine using Remote Desktop.
Apple makes its own "Remote Desktop" software, which is based off of VNC. You can only use it on Mac OS X, though, meaning you must use a Mac to view another Mac. You cannot use Apple's Remote Desktop software on a Windows machine.
Pretty much the only way you're going to get what you need is with VNC. There are several, free and commercial VNC viewers for Windows, including RealVNC, TightVNC, and others. A super-simple Google search for "VNC viewer" will get you what you need.
You then need to activate "Remote Management" in the Sharing pane of the System Preferences on the Mac. Under "Computer Settings..." you must specify a VNC password and enable "VNC viewers may control screen with password:".
That's it! You can now use a VNC viewer (set to 8-bit color) on your Windows machine to connect to and view the Mac using the Mac's IP address. If you're behind a router and/or Firewall on the Mac, you must open and forward the correct ports for VNC as well. If you're not familiar with port forwarding, more Google searches will get you pointed in the right direction for your particular brand of router and/or firewall. If both computers (Windows and Mac) are on the same network and not separated by any routers or firewalls, no port forwarding may be necessary, unless you've activated Mac OS X's own, internal firewall.