Good power supply for gaming computer?

hi there,
to answer your question properly it is imperative to know what hardware you intend to run.What processor you are thinking about(will you be overclocking),what video card are you thinking of(1 or 2 video cards?),how many hard drives,how much memory and what other hardware such as printer/scanner,how many dvd,cd drives you intend to install and what size is the case(reason being you want to ensure the pwr supply you purchase has long enough cables to be routed neatly in order to maintain proper airflow (I rec a modular pwr supply) A 300 watt pwr supply is not anywhere near sufficient to run even a low end system.Look into the corsiar hx620 for a good solid starter which promotes a clean install and is very efficient for its size that is of course if you are reasonable with your hardware selections.Thats my 2 cents ,I hope i have been somewhat helpful.

About the time this was posted, I built a mini ATX format desktop computer, using the Zotac IONITX-B-U motherboard with a 2Gig stick of DDR2 RAM. It runs a single core atom processor but has a special dedicated bridge to the onboard nVidia graphics chip to allow it to handle demanding 3D graphics without high power consumption.

The machine has performed flawlessly for 3 years now and could run Half Life 2 at full graphics smoothly, bogging down only when there was a lot of audio effects in one cut scene.
Run through a Kill-a-watt meter, the system idles at 18 Watts and peaks at 24 Watts. I can run it with a DC-DC converter at 12 volts from a battery powered by a solar panel.

By contrast, a newer Zotac IONITX-T-U boasts runs an Atom D525 (1.8GHz dual core) processor and can support 8 gig of DDR3 RAM. The onboard chip has a dedicated half gig as well. It ships with a 90 watt power brick, but you could do DC-DC conversion the same way that I do.
In spite of the lower processor speed, I bet it will be able to handle Diablo III effortlessly.

If you want to go low power, you need to rethink the big board and peripheral card bus mentality and think system dedicated to graphics.