You need to modify the VGA Cable (you can get adapter and modify it instead). This will allow any refesh rate, more sharp images if you VGA card can supply them. Most of the cards, cant because they lack the dedicated VGA output.
Connecting you monitor using DVI-VGA adapter will never give you same shapness and image quality as VGA-VGA connection, that is because manufacturers do not put all necessary components on the video cards nowdays for true analog VGA.
Image Showing PIN 12 location on VGA Cable – Disable PIN 12 to remove Auto Detect/PNP http://3.bp.blogspot.com/_N66od8KlQks/TD-St9qyYEI/AAAAAAAAAVU/K5fH6O4jx-o/s1600/vga_pinout.jpg
More on this:http://nookkin.com/content/allowing-any-screen-resolution-on-vista.phphttp://www.tomshardware.co.uk/forum/55329-29-converter-working-monitor-power-saving-mode