Hardware power is never enough. But should we buy new one. I think the best way is to squeeze out the most from what you got already. Since 1995 I've touched almost well know brand IBM, HP and Dell, from low and to enterprise, and I can say all of the are reliable and easy to mange, but … until you don't pay for them. So if you a start-up counting each pence in your pocket than you should choose the chip, easy upgradeable, easy recoverable hardware. As the "Automatism theory" says that you can build a reliable system if you use many unreliable components, means you can follow it as a mantra an build your rock solid solution.