Nope. Splitters will show the same image on 2 monitors and usually with significantly degraded quality.
Very good advice, if I may add... a good video card with onboard memory will not consume precious system resources which will slow down performance... Money well spent is on a video card and RAM if running XP 2MB is recommended and 4MB if running Vista (very hungry operating system) blue skies and tail winds...
Thank you for the correction, I specifically asked the Dell rep if the splitter would allow "extended desktop" functionality and he said it would... I personally prefer dual cards and am configuring my new XPS 710 accordingly. I was just passing on the information provided me.
Of course you can have extended desktop, but each monitor must have a separate video card port*, not a splitter. *some cards, like Quadro NVS, use a "Y-cable" which resembles a splitter, but it's functionally 2 separate ports.