RBTray is a free portable tool for Windows that allows you to minimize any window to the system tray.
How to use:
Just run the tool and right-click on the Minimize button of the window that you want to minimize to the system tray:
Now the window will be minimized to the system tray:
If you will right-click on its icon, it will show the following options:
It works in Windows 7, Vista & XP.