I think the refresh rates are good. I got them from the Sun web site. The display is working great except for the very small wraparound I'm getting (the right 1/4" wraps around to the left side).
After posting my last message, I reset my geometry to 1920x1200 and rebooted. When I do an xwininfo, I get this:
xwininfo: Window id: 0x1000003 ".gnome-desktop"
Absolute upper-left X: 0
Absolute upper-left Y: 0
Relative upper-left X: 0
Relative upper-left Y: 0
Visual Class: TrueColor
Border width: 0
Colormap: 0x20 (installed)
Bit Gravity State: NorthWestGravity
Window Gravity State: NorthWestGravity
Backing Store State: NotUseful
Save Under State: no
Map State: IsViewable
Override Redirect State: no
Corners: +0+0 -0+0 -0-0 +0-0
It looks like the driver is resetting to 1600.
One other note -- I'm using the 3123 kernel because the latest one (4191) doesn't work at all on this monitor.