That happens right after a fresh installation of the OS? Odd. Well anyway you don't need to install xorg (or any other X package for that matter), since if you do get a graphical login, X works. It's probably a settings problem or something equivalent..did it ever work?
If you want, you can try to rename some configuration directories from under your home directory to a different name, then re-login; if the problem is caused by a bad configuration, it should help (then you could delete those dirs; they're not "vital", but are re-created if missing - you'll just lose some of your personal settings, such as used theme etc.)
Have a look at your home directory's hidden files/directories (whose name start with a dot):
There are some, mainly .gnome, .gnome2, .gconf-something etc. that Gnome uses to store it's settings. You can try to rename (mv) those and relogin (ctrl+alt+backspace should restart X) and see if it has any effect. May or may not. Even easier way to check if it's about those settings directories is to create a new user with useradd, then set a password for the user with passwd and try to log in as that user. The newly created user should have no settings (or only default settings), so the problem doesn't affect it if it's about per-user configuration files. If the problem persists even with the new user, it's something system-wide. Remember to delete the user after the "test" with userdel.