Re: 7664 and 1600x1200 (maximum pixel clock?)
The "Supported additional Video Mode" comes from the monitor EDIDs. You can get that reported in your Xorg.log by increasing the logging verbosity of the X server. The best solution depends on how your distribution is set up, but invoking X like this should always work (note there are a total of 3 hyphens in there):
startx -- -logverbose 5
For me on Fedora Core 3, the permanent solution was to change these lines in /etc/X11/gdm/gdm.conf from:
command=/usr/X11R6/bin/X -audit 0
command=/usr/X11R6/bin/X -audit 0 -logverbose 5
Note that the monitor's EDIDs often report non-ideal modelines. On my 2001FP, the EDID supplies a 1600x1200 mode at 162 MHz, when in fact a 130.25 MHz mode (as seen above) achieves the same resolution without pushing the limits of DVI bandwidth. Your 2000FP will probably do the same thing.