They also use a thing called a RAID array on earth, perhaps that's what he's thinking. DX10 cards are going to be power hogs, and a powerful, well-made PSU will be a must. I've heard rumors as high as 250W. Servers are designed to be power-efficient, as companies have to pay power bills too, and may have hundreds of them. Desktops, not so efficient. Besides, even if he only uses, say 400W, that doesn't mean the other 300W are still being used, or charged for. Don't need a several hundred dollar tool to tell me that, just basic electricity theory.
Be that as it may but RAID isn't a be all end all for storage. You really should have a good reason to use RAID to make up for the headaches, real, potential and financial, that it poses.
I'll soften my stance- I suppose 3 drives (RAID 0 and a storage drive) or even 4 (RAID 0 and a RAID 1 for storage if you've got something to protect, think home business), but I won't soften my stance that 750W is ridiculous for anything smaller than a minicompiuter class machine (and PCs are not in that class, in case you were wondering).
Well, I'll grant you that RAID certainly isn't the be all end all for storage, however, it does add either security and/or speed, and with hard drives being as cheap as they are, why not? But that's beside the point; completely irrelevant to this forum post. Hard drives simply don't draw enough power for it to be relevant. I made my reccommendation based on the poster's stated intention of upgrading to a DX10 GPU. All reports state that these are going to consume prodigious amounts of 12V power. The poster also may want to overclock, neccesitating Vcore up to 1.5V and Vmem up to 2.3 or 2.4V. We'll take a moderate estimate of DX10 GPU power consumption; 200W, and suddenly we have a system drawing close to 500W. True, this is not close to 750W, however, if a 750W PSU is only providing 500W it is operating in the middle of its thermal envelope, whereas a 550W PSU would be operating near the very top of its respective envelope. Guess which will suffer more from capacitive break-down and other thermal effects? Which will add more heat to an already warm chassis? And the price difference is not so much ~$50. Your argument just doesn't hold up. 700W OCZ or FSP, and that's my final answer.