Thanks for all the help and advise, the xrandr post did the trick. It would seem that, by simply typing xrandr into a terminal session and it displaying the resolutions available, this sorted it out.
When I went back to screen settings, I have been able to set both monitors to 1680x1050.
Thank you ALL very much
Be Nice or Be Some Where Else
Linux i5-zebedee-DT1410-mint 3.2.0-23-generic #36-Ubuntu SMP Tue Apr 10 20:39:51 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux --