with just one DVI port if you use a splitter it will just clone the image to both monitors. If you have a Quadro GPU you will very likely have a DMS-59 connector on it and not a DVI port. This is a special port that allows two dvi signals to be sent through one port, the cable can then split this into two dvi or vga cables which you conenct to your motitors, this tech was developed to give low profile systems multi monitor support.
If you do only have one DVI port then a Matrox dualhead2go or triplehead2go will be your best bet imo. They allow you to strech your desktop accross the 2 or three monitors and use them independtly.