The premoistened towelettes that you can buy to clean the screen of your laptop computer (or at least the ones made by 3M, anyway) are basically lint-free disposable sheets soaked in a little water and isopropyl alcohol. Save your money and use a lint-free cloth and a little rubbing alcohol to clean your screen.

The cleaning pads you can buy, however, have the advantage of being sealed and thus portable while abroad.

Rubbing alcohol is also good for cleaning the chassis of computers, as well as the keyboards and heat sinks.