Chances are you aren't setting up your monitor correctly. If you have a manual, find the vertical and horizontal refresh rates, and set the resolutions allowed in your xorg.conf file (if you use xorgconfig, it will automatically save settings to your xorg.conf file, though you still have to set them manually).
If you don't have a manual for your monitor, find the model number and manufacturer (should be on your monitor somewhere) and look for an online specifications manual.
You will not be able to use a higher resolution or higher color settings without correctly setting up your xorg.conf file to reflect the settings of your monitor...your graphics card really has nothing to do with it.
EDIT: If you do want to manually set up your xorg.conf file instead of using xorgconfig, you will have to load it up into a text editor and change the correct areas. I'm not an expert when it comes to this, but I can find my way around the xorg.conf file when it's in front of me. However, I don't currently have a distro installed, so I can't tell you exactly what to edit, but it should be somewhere below graphics settings, and should have either "screen" or "monitor" in the title of the section.
If you're stuck in the command line, use the command
Code:
vim /etc/X11/xorg.conf
to load up your xorg.conf file, and edit appropriately. Be advised that vim is not the easiest text editing program to use, and would be much easier in a graphical environment.
If you're only seeing the command line, and not getting any default window manager, try using the command
in the command line after you log on to root from the command line. It *should* load up a graphical user interface for you to log on with, and you can use kedit instead of vim to edit your xorg.conf file.