In IRC, I asked for a bit of help getting my third monitor to become part of my dual monitor display and many posed interested in learning how I accomplished it (if I got it working). Well I got it working, so here is my xorg.conf. I hope it helps.

Code:
# nvidia-xconfig: X configuration file generated by nvidia-xconfig
# nvidia-xconfig:  version 1.0  (buildmeister@builder26)  Fri Dec 15 10:40:27 PST 2006

# /etc/X11/xorg.conf (xorg X Window System server configuration file)
#
# This file was generated by dexconf, the Debian X Configuration tool, using
# values from the debconf database.
#
# Edit this file with caution, and see the /etc/X11/xorg.conf manual page.
# (Type "man /etc/X11/xorg.conf" at the shell prompt.)
#
# This file is automatically updated on xserver-xorg package upgrades *only*
# if it has not been modified since the last upgrade of the xserver-xorg
# package.
#
# If you have edited this file but would like it to be automatically updated
# again, run the following command:
#   sudo dpkg-reconfigure -phigh xserver-xorg

Section "ServerLayout"
    Identifier     "Default Layout"
#    Screen         "Second Acer Screen"
#    Screen         "Default Screen" LeftOf "Second Screen"
#    Screen         "Polyview Screen"
#    Screen         "Default Acer Screen"
#    Screen         "Polyview Screen" RightOf "Default Acer Screen"
    Screen 0 "Default Acer Screen" 0 0
    Screen 1 "Second Acer Screen" RightOf "Default Acer Screen"
    Screen 2 "Polyview Screen" RightOf "Second Acer Screen"
    InputDevice    "Generic Keyboard"
    InputDevice    "Configured Mouse"
    Option         "Xinerama" "on"
    Option         "Clone" "off"
EndSection

Section "Files"

        # paths to defoma fonts
    FontPath        "/usr/share/X11/fonts/misc"
    FontPath        "/usr/share/X11/fonts/100dpi/:unscaled"
    FontPath        "/usr/share/X11/fonts/75dpi/:unscaled"
    FontPath        "/usr/share/X11/fonts/Type1"
    FontPath        "/usr/share/X11/fonts/100dpi"
    FontPath        "/usr/share/X11/fonts/75dpi"
EndSection

Section "Module"

#	Load	"GLcore"
#	Load	"dri"
    Load           "i2c"
    Load           "bitmap"
    Load           "ddc"
    Load           "extmod"
    Load           "freetype"
    Load           "glx"
    Load           "int10"
    Load           "type1"
    Load           "vbe"
EndSection

Section "InputDevice"
    Identifier     "Generic Keyboard"
    Driver         "kbd"
    Option         "CoreKeyboard"
    Option         "XkbRules" "xorg"
    Option         "XkbModel" "pc105"
    Option         "XkbLayout" "us"
EndSection

Section "InputDevice"
    Identifier     "Configured Mouse"
    Driver         "mouse"
    Option         "CorePointer"
    Option         "Device" "/dev/input/mice"
    Option         "Protocol" "ImPS/2"
    Option         "Emulate3Buttons" "true"
    Option         "ZAxisMapping" "4 5"
EndSection

Section "Monitor"
    Identifier     "Acer AL1916W Left"
    HorizSync       30.0 - 83.0
    VertRefresh     55.0 - 75.0
    Option         "DPMS"
EndSection

Section "Monitor"
    Identifier     "Acer AL1916W Right"
    HorizSync       30.0 - 83.0
    VertRefresh     55.0 - 75.0
    Option         "DPMS"
EndSection

Section "Monitor"
    Identifier     "Polyview Monitor"
    HorizSync       28 - 64
    VertRefresh     43 - 60
    Option         "DPMS"
EndSection

Section "Device"
    Identifier     "GeForce 7800GT Left"
    Driver         "nvidia"
    BusID          "PCI:5:0:0"
    Screen         0
EndSection

Section "Device"
    Identifier     "GeForce 7800GT Right"
    Driver         "nvidia"
    BusID          "PCI:5:0:0"
    Screen         1
EndSection

Section "Device"
    Identifier     "Trident Microsystems TGUI 9660/938x/968x (rev 3d)"
    Driver         "trident"
    BusID          "PCI:1:6:0"
    Screen         0
EndSection

Section "Screen"
    Identifier     "Default Acer Screen"
    Device         "GeForce 7800GT Left"
    Monitor        "Acer AL1916W Left"
    DefaultDepth    24

#    Option         "TwinView"
#    Option         "ConnectedMonitor" "LCD as 0,LCD as 1"
#    Option         "TwinViewOrientation" "RightOf"
    Option         "MetaModes" "1400x900"
    Option         "RenderAccel" "true"
#    Option         "SecondMonitorHorizSync" "30-83"
#    Option         "SecondMonitorVertRefresh" "55-75"
    Option         "NvAGP" "1"
    Option         "AllowGLXWithComposite" "true"

    SubSection     "Display"
        Depth       1
        Modes      "1400x900" "1280x1024" "1024x768" "800x600" "640x480"
    EndSubSection
    SubSection     "Display"
        Depth       4
        Modes      "1400x900" "1280x1024" "1024x768" "800x600" "640x480"
    EndSubSection
    SubSection     "Display"
        Depth       8
        Modes      "1400x900" "1280x1024" "1024x768" "800x600" "640x480"
    EndSubSection
    SubSection     "Display"
        Depth       15
        Modes      "1400x900" "1280x1024" "1024x768" "800x600" "640x480"
    EndSubSection
    SubSection     "Display"
        Depth       16
        Modes      "1400x900" "1280x1024" "1024x768" "800x600" "640x480"
    EndSubSection
    SubSection     "Display"
        Depth       24
        Modes      "1400x900" "1280x1024" "1024x768" "800x600" "640x480"
        ViewPort   0 0
    EndSubSection
EndSection

Section "Screen"
    Identifier     "Second Acer Screen"
    Device         "GeForce 7800GT Right"
    Monitor        "Acer AL1916W Right"
    DefaultDepth    24

#    Option         "TwinView"
#    Option         "ConnectedMonitor" "LCD as 0,LCD as 1"
#    Option         "TwinViewOrientation" "RightOf"
    Option         "MetaModes" "1400x900"
    Option         "RenderAccel" "true"
#    Option         "SecondMonitorHorizSync" "30-83"
#    Option         "SecondMonitorVertRefresh" "55-75"
    Option         "NvAGP" "1"
    Option         "AllowGLXWithComposite" "true"

    SubSection     "Display"
        Depth       1
        Modes      "1400x900" "1280x1024" "1024x768" "800x600" "640x480"
    EndSubSection
    SubSection     "Display"
        Depth       4
        Modes      "1400x900" "1280x1024" "1024x768" "800x600" "640x480"
    EndSubSection
    SubSection     "Display"
        Depth       8
        Modes      "1400x900" "1280x1024" "1024x768" "800x600" "640x480"
    EndSubSection
    SubSection     "Display"
        Depth       15
        Modes      "1400x900" "1280x1024" "1024x768" "800x600" "640x480"
    EndSubSection
    SubSection     "Display"
        Depth       16
        Modes      "1400x900" "1280x1024" "1024x768" "800x600" "640x480"
    EndSubSection
    SubSection     "Display"
        Depth       24
        Modes      "1400x900" "1280x1024" "1024x768" "800x600" "640x480"
        ViewPort   0 0
    EndSubSection
EndSection

Section "Screen"
    Identifier     "Polyview Screen"
    Device         "Trident Microsystems TGUI 9660/938x/968x (rev 3d)"
    Monitor        "Polyview Monitor"
    DefaultDepth    24

    SubSection     "Display"
        Depth       1
        Modes      "1024x768" "800x600" "640x480"
    EndSubSection
    SubSection     "Display"
        Depth       4
        Modes      "1024x768" "800x600" "640x480"
    EndSubSection
    SubSection     "Display"
        Depth       8
        Modes      "1024x768" "800x600" "640x480"
    EndSubSection
    SubSection     "Display"
        Depth       15
        Modes      "1024x768" "800x600" "640x480"
    EndSubSection
    SubSection     "Display"
        Depth       16
        Modes      "1024x768" "800x600" "640x480"
    EndSubSection
    SubSection     "Display"
        Depth       24
        Modes      "800x600" "640x480"
        ViewPort   0 0
    EndSubSection
EndSection

Section "Extensions"
#    Option         "Composite" "Enable"
EndSection
If you have any questions on how it works, I'll be glad to explain it.