Translations:Xorg/Guide/61/en
From Gentoo Wiki
Once the programs are installed, run startx again. A few xterm windows should appear, making it easy to verify the X server is working correctly. Once satisfied with the results, depclean x11-wm/twm and x11-terms/xterm if installed in the step above to remove the testing packages. They will not be needed to setup a proper desktop environment.