The power supply question is somewhat complex. Most systems draw 100 - 150 watts. PS efficiency must be taken into account as well as other factors.

Tom's hardware reviewed a number of ps's, i think most fried at the manufacturer's wattage claim and/or failed to perform within spec's.

To draw power at anywhere near the manufactures wattage claim creates high heat, and heat kills components.

I am unaware of any power supply that is not made in china, or if assembled elsewhere, the component parts are usually chinese.

Take a good look at your power supply. You pay say $60 for it and the manufacture gets $9. Can you begin to make a power supply yourself for that amount of money. I remember power supplies being many hundreds of dollars but will the consumer pay that?

For reliabilty and stability, I have been using 350-420 watt power supplies (depending on setups) and my customers are not having any mysterious problems. For most, 350-380 watt is cheap and good enough for most setups.

Overkill? maybe, but better safe for an extra $20.