The resolution in your /etc/X11/xorg.conf that you specified is too big. Go ahead and edit /etc/X11/xorg.conf, with nano (a small, very easy-to-use text editor). As root, type in "nano /etc/X11/xorg.conf".
In /etc/X11/xorg.conf, there will be a line that says "Section "Screen"" (no outer quotes). In there, there will be a line that says "Subsection "Display"" (again, no outer quotes). In fact, there may be several. That's okay--just find the one that precedes the line "Depth x", where x is the color depth you desire. Beneath that line, there should be a line that says "Modes XXXxYYY", where XXX is your horizontal resolution and YYY is your vertical resolution. You probably have 1024x768 as the resolution in there; try changing it to something smaller like 800x600. Save the file (Ctrl+O in nano) and exit (Ctrl+X). Then try to start X (type "startx" into the command-line), and let us know what happens