Sony VGN sz440 external display

hello

I have a sony laptop VGN SZ440 with nVidia Geforce GO 7400 as display
adapter. I have a Philips 190CW7CS/00 wide screen 19.1" monitor.
My problem is that the intensity and gray shades are so bad on the external
monitor I will not be able to read the label text under the icons on the
desktop as its in white color. Even the color plates in MS office will skip
the first 4 lines as shades are not differentiated (all look white).
I have the right drivers and updates for the display adapter for VISTA
Business and the monitor latest VISTA driver. but we are still facing this -
very bright no shades.
We changed the cable, we changed the monitor, worked with brightness,
contrast, we changed the laptop - yet still a VAIO with Vista on it - but
nothing changed. The only time it works perfectly when we place an XP machine
on it.
This has kept Sony, Philips and DELL dealers very confused with no answers.

I have already made the investment in the laptop and monitor and really need
to fix this. Anyone can help or guide!!! PLEASE

regards

Ray