Dell are now offering the OptiPlex 160 "Tiny Desktop". This is more commonly known as a "Net Top" computer, being made by taking the low power Intel Atom processor used in a netbook computer and putting it in a desktop case.
These units intended for point of sale applications and users running one undemanding application at a time (for example just web browsing). While capable of running Microsoft Windows, they would be better suited to Linux. Even the customer reviews on Dell's web site warn that the unit is too slow for high resolution video display.
The University of Canberra Library uses the OptiPlex 160 for online catalogue access. This application suits the low power unit as it requires running just one web browser window. In this application the unit was very responsive and was able to display some Flash animations without problems (I was not able to test video).
There are perhaps better and cheaper Nettop computers available, such as the ASRock, but these lack the corporate brand name of Dell.