If your DVI port is DVI-D, you cannot connect to VGA with a simple cable or adapter. DVI-D signals are digital, while VGA signals are analog. You'll have to use an electronic convertor box, available in either analog VGA to digital DVI
or digital DVI to analog VGA.
If you're still confused about which product to buy, our DVI cable guide has an easy-to-use chart to help you find the right cable for you. Or feel free to give us a call if you have any questions. We're happy to help you get the cables you need!