PowerStrip was originally designed as an enhanced replacement for the Microsoft Windows QuickRes utility, and like QuickRes it runs as an icon on the system tray - next to the clock. You access PowerStrip by clicking on this icon, and selecting from the popup menu that appears on screen.
By default, the PowerStrip menu is also accessible by pressing Ctl+Alt+P at any time - for the benefit of users with overscanned desktops.
Note that the PowerStrip icon in the system tray can be changed to one of your own choosing, or disabled altogether.
Windows 7: Needless to say, unless configured by you otherwise, system tray icons are hidden in a single group under Windows 7.