Here is another one: http://www.xilinx.com/bvdocs/appnotes/xapp535.pdf . It's an application note from Xilinx. It has some useful info on how to handle the VGA signals plus some more on the subject (a hardware display controller for a 640x480 resolution VGA screen capable of showing up to 256K colors and designed for the NEC TFT Color LCD Module NL6448BC20-08 that is mounted on the Xilinx ML300 board).