I work as a software developer for a small e-commerce firm, named after a large river. The most common use case for me, is to have my laptop docked to a larger screen, where I have some applications running on my laptop screen, this could be a browser window on a laptop screen, e-mail client etc., and have my ssh windows open on the bigger screen, since code is more important to me, it gets the larger screen real estate. Linux, (maybe not Unity) but KDE, SUCKS MY BALLS for this. This is the most common use case for EVERYONE working in my company, and Linux is completely unusable for this. 1. lightdm, the display manager, will not understand the desktop monitor settings. 2. The extended desktop setting is broken. On the OPEN SOURCE, Intel driver. Just in case someone started bitching about drivers. 3. If you force it into your required setting, with the bigger screen as your main display, and the smaller screen as extended to it's side, the brilliance that Linux is, will show a blank screen if you aren't connected. Basically, if you are connected things can be OK for one big screen, if you are not, it will still try to push display to the bigger screen, even when you ARE NOT connected. I have many more grievances against extended displays on Linux, but I will stop here. Basically, Linux on multi monitor set ups, is a non-starter. Note : I might have used Linux as a stand-in for KDE, so this might just be a rant about KDE, but I tried XFCE on my home laptop. The out-of-box experience is so 90's that it beggars belief. Win7, it pains me to say, is smooth as butter on this. Every imaginable configuration, is done as intuitively as possible. The Win+P shortcut brings up an easy mode switching popup. The advanced configuration screen under Screen Resolution, is super easy to figure out as well. Also, the grand-grand-parent poster, is absolutely wrong about the Window Manger being linked with the application in Windows. From Vista, Windows has had a compositing manager, no dirty rectangles, tearing the screen because of one misbehaving application. Yes, I understand the reasons for why Linux/KDE isn't able to do this, lack of vertical integration, no driver support, blah blah, but really, how can I evangelize about Linux, if it cannot do something as simple as extending displays correctly and easily?