Problem getting proper color resolution on E172FP after Windows XP reinstallation

I had to reinstall my Windows XP.  I did so using the Dell disc that came with my Dell pc.  The problem is that the color resolution is wrong and I cannot figure out how to fix.  If I go to control panel\appearance and themes\display\settings the color quality shows "LOW (8 bit)" and clicking on the pull-down does not show any other options.  I should have 256 colors right?  The colors look wrong since reinstalling my Windows XP.  Can anyone help?