will need a dedicated graphic card installed. Most cards will have 2 monitor ports (dvi, hdmi or vga) on them. Before you go get a card, make sure you know your max power supply wattage. Most hp computers have between 200 and 300 watts. Graphic cards start at 270 watts for some ATI cards and it goes up from there. It will also need to be a PCI Express graphic card. If you have the misfortune of having one of the hp mini-towers (s3000 series) you will have to get a low profile graphic card. Good Luck!
i have a desktop and want to be able to have two monitor(flat screen) runing at the same time. running window vista on an hp, what is the hook up for it to work.