I will show you how to HACK the windows logon page allowing you to change a admin accounts password or ever open a browser on the logon screen!
Real VNC and Tight Vnc are screen sharing software that allow you to control a computer/mac from windows/mac/ipad/iphone/android etc.
It is a simple application just Download it from here and follow the instructions.
Then just locate the icon in the notification area and just hover over it and it will show a Ip Address Eg.192.168.1.1
Now download a vnc viewer from Google Play Or Itunes and connect your device to the same router as the computer and enter the IP address, And you are Connected!