Go to the “View” Menu and click on “status bar” so that a check mark appears next to it. You should now have a visible bar at the bottom of the screen, on which the NoScript icon will be located. I use Windows XP, but I’m assuming the behavior would be the same for both operating systems.
I have the status bar at the bottom of the screen, but there isn’t any ‘S’ icon or anything else permanently displayed on it. Doesn’t really matter anyway, since I can easily access the Option menu through Tools. Thanks, though.