I have connected a laptop to my pc through my monitors VGA cable but color resolution wont go more than 8bits and resolution is stuck and 800 by 600. Then installed the graphic card driver and i could use it. Did this setup as my uncles old laptops display was not working. IF you have not installed the graphic card driver, and if your laptop monitor is not working do the following
1- Connect your monitor
2- Switch on the monitor and your laptop
3-Keep pressing f8 until on your monitor you see a menu
4- Select Vga mode.
5-Windows will load and install your graphic driver.