How would this look on a WS display? Do these monitors stretch the 4:3 resolution to fit the full screen or do they use black bars at the side? (I think I'd prefer the latter so the text would be the sharpest.)
In the display drivers for your laptop, there should be an option for how it handles the external display. You should be able to select either a scaled output (where is stretches the image to fill the screen, no black bands), a centered image (which keeps the aspect ratio of the resolution you choose, but stretches to fill as much of the screen as it can, possibly has black bands to either the top/bottom or left/right of the image), or perform no scaling at all (which keeps the resolution as is, usually centered on the screen, possilby has black bands around image).
If you leave it up to the monitor to scale the image, chances are that it will scale to fill the screen. and you will get a distorted image.