These days whenever you try to buy/build a PC, you constantly see demands and suggestions for large power supplies. 400W seems to be for low-end machines, Real Men need at least 500W, but if you intend to do gaming, better get at least 650W, etc. In one MB manual that I'm considering to buy I even saw a suggestion to buy a 1000W PSU if you intend to install a serious VGA.
But how much of this is true, and how much of this is sweet-talk by marketing weasels? From personal experience I can tell that for years I've been happy with 300W PSU's, and now, when I recently put together a fairly mid-to-high-end gaming machine it runs just fine on a 400W PSU. And that's with a Phenom II X2 550 Black Edition, MSI Radeon 4850 OC, 2x1GB Corsair DDR3 RAM, 2xHDD, 1xDVD-RW, plus a bunch of lesser power-consumers like fans and USB peripherals.
Am I risking something? Can the system just go up in smoke one day because I've selected a PSU too weak? Or is 400W really enough for most needs and the whole wattage-hype is way too overrated?
Note - I do understand that there are cheap low-quality PSUs out there that boast a power rating way higher that they can actually support. I'm not talking about those. I'm talking about decent PSUs from manufacturers with a good reputation that can be trusted to deliver close to the power they promise.