Dell 2005FPW runs at 1680x1050 but looks much lower...?

I'm running KDE on FC3 using a Dell 2005FPW at 1680x1050.  The problem is
that it _looks_ like its running at a much lower resolution.  I know its a
Linux (or xorg) problem because when I run the same resolution in Windows
XP, it looks as expected:  very small and sharp.  Any ideas?  Here is my
relevant xorg.conf sections:

---
Section "Monitor"
        Identifier   "Monitor0"
        VendorName   "Monitor Vendor"
        ModelName    "LCD Panel 1680x1050"
        HorizSync    3.0 - 83.0
        VertRefresh  56.0 - 75.0
        ModeLine "1680x1050" 146.2 1680 1784 1968 2256 1050 1051 1054 1087 -hsync
-vsync
        Option      "dpms"
EndSection

Section "Screen"
        Identifier "Screen0"
        Device     "Videocard0"
        Monitor    "Monitor0"
        DefaultDepth     24
        SubSection "Display"
                Viewport   0 0
                Depth     24
                Modes    "1680x1050"
        EndSubSection
EndSection
---

Thanks for the help.