Flickering screen with FC1 and Dell 8600

[Chris Jones <jonesc hep phy cam ac uk>]

Hi,

I have a inspiron 8600 laptop with a WUXGA 1920x1200 screen and a NVIDIA 
Geforce4go 5650 video card with the NVIDIA 5336 drivers installed. I am 
trying to get the graphics to work properly with Fedora Core 1.
After searching through the wbe etc. I have found a set of options which 
seem to work but the screen suffers from occasion flickering.

My XF86Config and Xfree.0.log files are
http://www.hep.phy.cam.ac.uk/~jonesc/8600/XF86Config
and
http://www.hep.phy.cam.ac.uk/~jonesc/8600/XFree86.0.log

This is my first experience of installing linux on a laptop, so please 
forgive any mistakes or newbie-status.
My questions are

Have I configured X correctly ? I found a number of ModeLines which give 
different refresh rates i.e.

        #1920x1200 @ 52Hz
        #ModeLine    "1920x1200" 162        1920 1984 2176 2480 1200 
1201 1204 1250 +hsync +vsync
        #1920x1200 @ 60Hz
        Modeline     "1920x1200" 161.750000 1920 2020 2052 2184 1200 
1202 1208 1235 -HSync -VSync

Is one better than the other ? Also are these correct (again I have 
found various versions)

        HorizSync    31.5 - 100.0
        VertRefresh  30.0 - 90.0

Has anyone else with this hardware experinced flickering ? Could it it 
something else (DPMS ?) I am running kdm desktop with KDE 3.2.2.

Chris