I just installed the nVidia graphics drivers, and now my screen resolution is tiny- it seems as though it has a resolution of 640x480.. but I am not sure.. (The screen doesn't go to the maximum possible size of the hardware-- there is approximately an inch of black unused space around the outside of the "viewable area") The maximum resolution on my laptop's monitor is 1024x768.. this is the resolution I want.

here is my XF86Config for the video settings:

Section "Monitor"
Identifier "Monitor0"
VendorName "Monitor Vendor"
ModelName "Unknown monitor"
HorizSync 31.5 - 37.9
VertRefresh 50.0 - 70.0
Option "dpms"
EndSection

Section "Device"
Identifier "Videocard0"
Driver "nv"
VendorName "Videocard vendor"
BoardName "nVidia GeForce 2 Go"
EndSection

Section "Screen"
Identifier "Screen0"
Device "Videocard0"
Monitor "Monitor0"
DefaultDepth 24
SubSection "Display"
Depth 16
Modes "1024x768" "800x600"
EndSubSection
SubSection "Display"
Depth 24
Modes "1024x768 "800x600"
EndSubSection
EndSection

please help!!
also, In the display settings in gnome, it says that my resolution is 1024x768, while its not..

When you installed the NVIDIA graphics drivers you should have edited this file, change the line:
Driver "nv"
To
Driver "nvidia"

And be sure to comment out (place a pound sign # in front of) these lines near the top:
LoadModule "dri"
LoadModule "GLcore"

Also, make sure you have created, or uncommented this entry:
LoadModule "glx"

Save the file, restart X and try again

Cool

have you made sure your monitor's horizontal and vertical refresh rates are correct?

i have 2 question , how to change the refresh rate and why i can't change to a 32 bits color screen instead of 24 bits

well you will see in the monitor section that you can specify refresh rates, and in the screen section you prolly don't have the 32bit depth level