Gaming and power consumption
Intel has made solid progress with its homegrown HD Graphics over the past five years. The Celeron version is equipped with the least powerful iteration, and any score sub-1,000 usually indicates that the system will not be able to handle modern games at sensible resolution and image quality settings.
A fact graphically borne out by the Aliens vs. Predator test. It would be a mistake to consider this small-form-factor PC for anything resembling serious gaming. Approaching gaming from the casual angle - in-browser, mainly - leads to a different, more positive conclusion. The HD Graphics are more than capable of running games such as Plants vs. Zombies, Runescape or Quake Live.
Powerful performance and energy efficiency usually don't go hand in hand. The VivoMini UN42 is a miser in the power stakes - we never saw the consumption rise above 20W at any time - and this bodes well for an always-on, always-connected PC for media duties.