External Monitor on 12" PowerBook with NV17 (PCI Id 10de:0179):
add

Option          "CrtcNumber"            "0"
Option          "FlatPanel"             "0"

in the "Device" Section of XF86Config-4. The monitor has to be already plugged
in during system startup. This works at least with XFree86 4.3.99.14.
 -- Guido <agx@sigxcpu.org>