To answer your question, yes you can use it, even if you only have a normal monitor, by using a
DVI-VGA adapter. Most cards come with one included, so check the box or wherever you put the bits that came with it. If not, you can buy one for about a £5. Depending on your video card, you may, or may not, then be able to run two diifferent displays. e.g.
Matrox G-550.