Is it the monitor described here?
If so, to quote
The Dell E207WFP LCD monitor’s fast 5ms response time, high contrast ratio and 1680x1050 resolution...
the closer you get to the native resolution (1680x1050) the closer to unstretched the picture will appear (and probably anyth significantly away from the natural res will make the picture lose definition, or lose something at the edges).
If it is a described on that page, I don't understand your comment C.
And when you say
Even If I change to 1400X1250.. this does not work..
do you mean that the display does not work at all, or that it does not display unstretched (unsurprising).
Also don't be over-ambitious with the scan frequency, or maybe it won't sync. Once you've got it unstretched you can try increments in scan frequency (and revert, if you go too far).