http://www.tftcentral.co.uk/ is always a good reference, especially if you are worried about colour reproduction at all.
Most 21" monitors are only 1680 x 1050, though a few higher res ones are creeping through.
I suggest your CAD guy is against widescreen because he has used an incorrectly set up widescreen that stretched the image horizontally, making it unusable for CAD (as all the circle would look like ellipses etc). This isn't an issue if you make sure your display card is outputting the same resolution as the monitor.
(e.g. if Display->Properties in Windows is set to output 1024×768 to a 1680×1050 monitor then the result is horrible, blurry and distorted – but it is amazing how many people don't realise this and soldier on).
Bit like the huge number of people that either don't know about or don't properly tune ClearType on Windows and soldier on with horrible jaggy text.
takisawa2: that's definitely not HDMI-compatible.