I remember having a similar issue with a computer and wide screen on Fedora 7. It didn't recognize the 1440x900 resolution that I was trying to configure and I don't believe the monitor was listed in the setup. As far as I understand, the X Window System doesn't use drivers to interact with the monitor, you just have to tell X what the range of valid horizontal and vertical frequency range. You may want to check Samsung's website to see if the specs for that particular model can give you a hint, then edit the xorg.conf file in /etc/X11/. You'll also have to edit the xorg.conf file so that it has the resolution you're trying to get at.
On a different note, does X not respond when you press <CTRL> <ALT> <Backspace>?