Question about PCIe slots

So here I am thinking about going to HD/Native, and it occurred to me that I better see what slots I have available in my computer. I only have a full length PCIe slot open(x16?). Now I DO have a graphics cards with the short(x1 is it?) PCIe config sitting in a full length slot and it works fine, so the question is; will the HDN card work in a full-length slot??