First let me give you an idea of my situation.

I've got two SSDs for programs and OS as well as a 1TB 7200 RPM Steagate Barracuda for storage, playback of movies (HD included) and a handful of old programs that are used sparingly.

The Barracuda is the loudest thing in my case right now, *even though* it's suspended via elastic bands and idle most of the time. I've achieved this thanks to gratuitous aftermarket heatsinks and lots of GTs spinning very slowly.

Anyway, the Barracuda is starting to fill up. It always seems the storage hard drive upgrade one makes will last them practically forever. But as usual, it always fills up. ... not only that but the more one has the greater the loss if the drive fails.

So I'm thinking of demoting the Barracuda to a backup drive and getting a 2TB for main storage. I don't have room physically and acoustically for more than one 3.5" HDD in my case so this is the only option.

So, here is the question:

What is the best ~2TB drive for my situation?

There is no budget to worry about here... I guess $200 at most but the 2TB drives these days go for $150 or so, and half that for the green ones.

The trouble is these drives are painfully slow in the benchmarks. Sub 100MB/s transfer, 10ms+ response.

I've got a few HD movies on the barracuda that I watch directly from it. I worry that with a slower drive I would loose perfectly smooth continuous playback.

So is there any HDD out there that is (hopefully) about as fast as a 7200RPM Barracuda, yet quieter?

Video playback is such an easy task for todays harddrives that you don't need to worry. I run some lighter games from my EcoGreen's and even there it's only a matter of maybe 20% longer level loading times. Any new "green" 5400'ish RPM drive should be fine for your described use and a lot quieter. While I couldn't really complain about the noise that my three 7200 RPM HD103SJ's were making, once I compared them to EcoGreen's their fate was sealed, even if I could have kept one for games. Thanks to increased data density todays 5400 RPM drives aren't bad as long as you aren't running the OS from them.

I did a small test running several 1080p h.264 movies from a HD204UI drive and two simultaneous movies played smoothly and seeked reasonably well. Three did not go well at all however, although on my plain dual core system neither did it when running the movies off an SSD. Possibly there's also a limit in the video acceleration as the driver crashed at one time. But I'd say it's fair to assume that two movies at the same time to be the limit for this drive. One is a piece of cake and I frequently watch movies on a drive that has some lighter background duty as well, like downloading or so.

Who cares about these benchmarks? These numbers are wrong anyway.

A modern "green" drive will have transfers as fast as an old Barracuda.

Want more performance? Get more drives or get rid of whatever software interferes with your drive ("anti-virus" and whatnot).
You could also get a marginal improvement by partitioning your drive in such a way as to make it faster.
Or you could get a faster drive but that would be a waste. Regardless, if you want fast, don't just look at the marketing and the rpms: you want a high-density drive. Today, that means you want a drive with 1T platters. There aren't a whole lot of them around yet and so far as I know they're all 7200 rpm.

Just go with green drives, new 2tb drives have good transfer rates, the only missing is response, but you got your ssds for OS/programs. WD Caviar Greens are considered the most silent of them all, but personally i prefer Hitachi 5k3000, Samsung F4 are also very good drives.

A straight Blu-ray rip is at most, 40 mbps (5 MB/s). Any hard drive made in the last 10 years can deliver that.

If you're going go suspend it, the Hitachi 5K3000 would be my choice.

Apparently, Hitatchi is shipping their first 1TB platter drives as of yesterday in both 5X00 and 7200 RPM varieties, though they're only single platter disks, so no 2TB drives from them yet. If they perform like the 5K3000 drive SPCR recently reviewed though, they might be another good lower-rpm option. In the mean time, the 5K3000 might be worth looking at. Better performance than the other "green" drives, but with significantly less noise than a 7200 RPM drive.