1) Dell Latitude D520 with the Intel 945GM Chipset
2) Dell SE178WFP with the VGA cable
3) Dell D/Port
When the laptop is directly connected to the display, the video works fine. When the display and laptop are both hooked to the dock, there is no video. Instead, I get a message which says "Cannot display this video mode." The old CRT will work when connected to the dock.
Is there no video only on the external display, or on both the laptop and the external monitor? If only on the externam monitor, your resolution and/or refresh rate is probably too high. Use both screens, and set the resolution on the second display. For a 17" LCD, you probably will be using 1280x1024 at 60hz. If you had a CRT before you may have had it at some odd refresh rate that the LCD can't display.