|I am searching such a solution since 2 months…|
It is not a graphics card. Rather it is a palm-sized box that sits outside of your system. DualHead2Go takes the existing single monitor display output (i.e. external VGA output) from your system and expands it into dual display outputs, allowing you to run your Windows desktop at up to 2560 x 1024 resolution stretched across two displays. Using DualHead2Go in conjunction with the built-in display of your laptop, you actually benefit from 3 displays at a time.
read the detailled presentation at Matrox.com