If I read that spec sheet right you have a video card the computer shipped with, correct? That would be why It says (0). You already have a card in that AGP slot.
the card lookin4help suggested is PCI-e which will not work with the AGP slot you have in your computer. There are a few very expensive AGP cards with dual DVI but all cards in your price range will have 1 DVI and 1 D-sub port. The same 7600GT for AGP is $170+ so here's a ~$110 AGP card.
Its got 512MB memory and is only $85 after rebate.