I really like Xfce 4.4's compositor [giving me nice shadows, transparent windows et al], and I wanted to clean up, so I requested Mephisto's really minimal xorg.conf [which he uses with X.org 7.2 and an nvidia 9746 driver]. I added some modules that wheren't automatically loaded by my X.org 7.1, and some stuff to get composition. This is the result:

Section "ServerLayout"
    Identifier  "Default"
    Screen      "Screen" 0 0
    Option      "AllowDeactivateGrabs" "1"
    Option      "AllowClosedownGrabs" "1"
EndSection
Section "Device"
    Identifier  "Nvidia"
    Driver      "nvidia"
    Option      "NoLogo" "1"
    Option      "DynamicTwinView" "0"
    Option      "AddARGBGLXVisuals" "1"
    # Composite stuff
    Option      "RenderAccel" "true"
    Option      "AllowGLXWithComposite" "true"
EndSection
Section "Screen"
    Identifier  "Screen"
    Device      "Nvidia"
EndSection

Section "Module"
    Load        "glx"
    Load        "dbe"    # Double buffer extension
    Load        "extmod"
EndSection

Section "Extensions"
        Option      "Composite" "true"
EndSection

I hope this may be of use for someone else out there :) It works on my Debian sid workstation with X.org 7.1 and nvidia binary 9631 driver.