According to Microsoft:
"Wouldn't it be great if you could read an e-mail message, confirm a meeting location, or check a flight reservation without turning on your computer? What if you could check the program guide in Windows Media Center by using a display that's built into your remote control? Windows SideShow puts this information literally at your fingertips on a wide variety of devices that can retrieve information from your mobile PC or desktop computer.
Windows SideShow is a new technology in Windows Vista that supports a secondary screen on your mobile PC. With this additional display you can view important information whether your laptop is on, off, or in sleep mode. Windows SideShow is available in Windows Vista Home Premium, Windows Vista Business, Windows Vista Enterprise, and Windows Vista Ultimate.
Windows SideShow uses gadgets, convenient mini programs, to extend information from your computer to other devices. Gadgets can run on a Windows SideShow–compatible device and update that device with information from your computer. Using a gadget, you can view information from your computer regardless of whether your mobile PC is on, off, or in the sleep power state—which can save you both time and battery life."
This is all wonderful visuals but the reality is that Microsoft marketed SideShow as this amazing feature then virtually stopped all development of gadgets to support it.
The other blaring issue is that the W5Fe and all other SideShow enabled devices must use Windows Vista as an OS to use the external displays. Without Vista these displays will not function. So essentially you have bought a laptop that is stuck with one OS for its' entire life.