Voldemort,
here's a copy of the start of your Section "Monitor"

# Auto-generated by KNOPPIX mkxf86config

Section "Monitor"
Identifier "Monitor0"
Option "DPMS" "true"
VendorName "DEC"
ModelName "DEC06da"
HorizSync 30-86# DDC-probed
VertRefresh 50-130# DDC-probed


To get Twinview (two screens under nvidia driver) working here's a copy of the same portion of mine;


# Auto-generated by KNOPPIX mkxf86config

Section "Monitor"
Identifier "Monitor0"
Option "DPMS" "true"
VendorName "VSC"
ModelName "VSC4f4d"
HorizSync 30 - 97 # DDC-probed
VertRefresh 50 - 180 # DDC-probed
Option "Twinview"
Option "SecondMonitorHorizSync" "30-97"
Option "SecondMonitorVertRefresh" "50-160"
Option "MetaModes" "1280x1024,1280x1024"

Voldemort, take careful note of the following. In mine, the only thing added to get mine working is ;
Option "Twinview"
Option "SecondMonitorHorizSync" "30-97"
Option "SecondMonitorVertRefresh" "50-160"
Option "MetaModes" "1280x1024,1280x1024"

No other changes are required to XF86Config-4. Be careful that the vertical refresh rates for your screens are roughly the same according to the manufacturers spec. If they are really different you might have problems. You will have to change the refresh rates to match those of your second screen and the 'MetaModes' line to the resolution you want. OK?

Let me know if this works.

Regards,
Jim