I have doubts that a $60 terabyte drive could live up to the claim that it would use less power and generate less noise and heat than your average hard drive.

It is definitely very quiet and does run cooler. This is a "green" 5400 RPM drive, it's made to do what they claim and it does it well. It's also 64MB cache, they get it wrong on here every time.

#1, it depends on what you consider an "average" hard drive. The larger capacity, newer drives will probably have higher density platters and also less platters total.

to #2; what does "green" or "black" mean in these deals? where can i find this information? thanks for this type of question.

Green or Black (also Blue) are just the groups of diffrent drives that WD makes. Green as you would imagine is more eco-friendly and typically use less power and produce less noise. They usually run at 5400rpm and around 6 watts. they are not suggested for gaming, streaming HD, or anything else that might be labor intensive to a drive (like your operating system). But they are great for a secondary drive to dump all of those photos you will never look at again.
Blue and Black are faster, louder and use a bit more juice respectively. They are better for primary drive usage and more intese applications. You just have to figure out what you need and then buy the color that fits.

#1 is being silly. It uses less power than the average same-generation drive due to lower RPM than average (7200), and as little or less than older drives due to needing only one platter to achieve 1TB.

Not sure where #5 gets the idea they are not suggested for streaming HD, since they are multiple times the throughput of any HD format on the market, certainly fast enough to watch 2 or 3 HD movies concurrently on different clients.

Desktop systems benefit less from low latency that some other uses of a computer, especially these days when a merely average system has 4-6GB of main memory to cache I/O. Most people would never notice the difference except in a benchmark highlighting latency differences, unless they were only contrasting a new current-generation drive instead of the typical 1 or more generations older drive they want to supplement or replace.

thanks to #5