If they are using a TFT screen, then running it at a non-native resolution will make the text blurry, as it's trying to spread 1 pixel across 1.2 pixels (for example) - and it won't work and has to guess.
This will cause the eyes to constantly try to focus this blurry text, causing fatigue and headaches.
Most decent applications allow you zoom the content - certainly all major current web browsers, as well as the Office suite (Word, Excel etc) - this will provide a much better experience.