If you're using an LCD screen, you'll find that Adobe Gamma won't work. It's not designed for LCD screens.
If you were using a CRT, the directions are correct. You should maximize the Contrast, then adjust the brightness until the square interior box "just disappears" . That is the optimal point. You never again adjust those settings until the next time you want to calibrate ( perhaps every month or so ).
You might look at this thread, brent bertram "fpd monitor with dvi connection" 7/31/03 4:15pm </cgi-bin/webx?50.1dea242e/6> in the Color management forum, and check out Ian Lyons' review at <http://www.computer-darkroom.com/ione/ione-1.htm> . I don't know of a free application ( like Adobe Gamma ) to calibrate and profile an LCD display . Perhaps , in the future, Adobe will provide such a utility, but not so far.
As to the color management setup, I always use full color management ( best for print, using the AdobeRGB colorspace ). The profile you create with Adobe Gamma is used regardless of your choice of color management mode. That profile, loaded by the Adobe Gamma Loader.exe at boot time, adjusts your image view to the standard "calibrated" state in any color managed application.
Ian Lyons Image Flow <http://www.btinternet.com/~ian.lyons/ps7-colour/ps7_color.gif>