Many times I have wondered, how come a person, able to work on two pc simultaneously, at the same time. I remember in one of the Google Company videos where a guy (Google Employee) would be working in two big PCs. It takes me, almost more than a year, to realise that its not two PCs, its just two monitors with extended desktop option provided by the operating system. In those days, it was surprising for me, but now, it was part and parcel of my everyday life. Anyways, Its a great option by which can drag and drop application across the monitors.It was very helpful. Particularly, In my case, as a web application development, where I can code in one monitor and can refresh the browser on the other monitor. If I were doing some documentation. I would open my mail box in the one monitor and keeps doing on the documenting in other monitor. It makes the life simpler and working more effective. (at the cost of electricity).. So I would recommend anyone who buys a laptop to buy another monitor. so that he can watch movie/video songs in one monitor and simultaneously work on Laptop :) . Its simply the Excellent option..Here is the link that explains how to do that..http://www.microsoft.com/windowsxp/using/setup/learnmore/northrup_multimon.mspx
A straight summary of the above link in windows XP, Extended Desktop Option lies in the Desktop Right Click -> display Properties -> settings tab .