Yes, the terabyte hard drive is available in a way. But this is actually two hard drives strapped together than run off of one logic board so it is not truly a single drive.
Drive advance fuels terabyte era
A single hard drive with four terabytes of storage could be a reality by 2011, says Japanese firm Hitachi.
Ref. https://news.bbc.co.uk/1/hi/technology/7044606.stm
It's all well and good to keep increasing the capacity of hard drives, but unless they improve the rate of transfer between media then it is still prehistoric.
Actually, the transfer rate they're using now is more then enough. The problem is the physical limitation of the hard drive itself (Speed of the platters, how data is transfered from the head).
Bigger caches are making things better, but no matter if you have a Serial ATA 150, 300, or the upcoming 600, the speed will still probably not go over 80MB/s
The only exception is the Western Digital Raptor series. These are 10,000 RPM hard drives, albeit with limited capacity (150GB is currently as high as it goes).
What I plan to do one day is get a 74G Raptor for Windows, a 150G raptor for all my games, and a 500G+ 7200RPM normal hard drive for my videos, documents, and other misc stuff.
I disagree that 160 is more then enough, cause it's not for some people. I used to have a 160 and ended up with only 30-40G left after a bunch of downloads (Of course I have like 90Gigs of games alone). I now have a 500G drive and ghosted my old one to it so I don't have to deal with re-installing 2k
80-160 is more then enough for 'normal activity'. But for gamers and video/audio editing, it's really not
And yes, terabyte hard drives can be made from 2 500G drives from ether using Raid, or windows dynamic disk.