> what used to take hundreds of disk drives to store, you can store on 1 today
Though, given that hard drives very much do not obey Moore's Law, a well-designed 1998 solution with hundreds of disks may well have far faster IO than the 2012 one-disk solution.
What really changed is you don't need to use 1998 approach to solve the same problem. A single SSD can beat 50 1998 HDD in terms of IOPS, storage, latency etc. Your PC probably has more RAM now than you had HDD in 1998 and CPU's have almost as much cache a 1998 computer.
PS: A traditional HDD is hard pressed to break 200 IOPS / second cheap SSD's easily 100x you can break 100,000 for well under a grand. http://en.wikipedia.org/wiki/IOPS
Though, given that hard drives very much do not obey Moore's Law, a well-designed 1998 solution with hundreds of disks may well have far faster IO than the 2012 one-disk solution.