1920x1600 does not sound like widescreen to me at all.  Are you sure that is the native resolution of the external monitor?   Widescreen aspect ratios are usually well over 1.6 while 1920/1600 is less than 1.2.

Balaji you are right- I made a mistake. I should have said that the native resolution of the new24" monitor is 1920 x 1200. Lo and behold, now that I adjust the resolution, things work fine. Sometimes I guess I let my own perception of my intelligence stand in the way of actually being insightful. Thank you for your help, it is much appreciated.