Here's my relevant part of the xorg.conf (it works), different card,
most likely same driver though. This also allows beryl to work.
Identifier "GForce 6200"
Driver "nvidia"
Option "IgnoreDisplayDevices" "TV"
Option "Coolbits" "1"
Option "RenderAccel" "1"
Option "AllowGLXWithComposite" "1"
Option "RandRRotation" "1"
Option "AddARGBGLXVisuals" "1"
Option "DisableGLXRootClipping" "1"
Option "TripleBuffer" "1"
Option "UseEDID" "1"
Option "UseEdidFreqs" "1"
Option "DynamicTwinView" "0"
BusID "PCI:1:0:0"
VideoRam 131768
Option "NoLogo" "TRUE"
Option "NvAGP" "2"
Option "DigitalVibrance" "0"
Option "TransparentIndex" "0"
Option "CursorShadowAlpha" "64"
Option "CursorShadowXOffse" "4"
Option "Twinview" "1"
Option "TwinViewOrientation" "clone"
Option "SecondMonitorHorizSync" "30-50"
Option "SecondMonitorVertRefresh" "60"
Option "Xinerama" "0"
Option "MetaModes" "1280x1024 , 1024x768"
Option "ConnectedMonitor" "CRT , TV"
Option "UseInit10Module" "true"
Quite a bit of difference I would say. Keep in mind the NvAGP may not
be appropriate for your card, if in doubt, set that to 0.