I have a new iBook but unfortunately sold my 21" CRT before I got a chance to try this out... the iBook's video out only supports mirroring, which means the same image is displayed on the built-in screen as on the monitor. The built-in screen can not be turned off, although can dim it all the way.<br><br>As for the higher resolutions on your CRT... this *should* be possible; the built-in screen will simply be black when you're running the higher resolutions (since it can't display them).<br><br>