[derobert]

    $ iostat -kx sda sdb sdc sdd
    Linux 3.1.0-1-amd64 (Zia)       12/19/2011      _x86_64_        (8 CPU)
    
    avg-cpu:  %user   %nice %system %iowait  %steal   %idle
               0.93    0.02    0.72    0.25    0.00   98.08
    
    Device:         rrqm/s   wrqm/s     r/s     w/s    rkB/s    wkB/s avgrq-sz avgqu-sz   await r_await w_await  svctm  %util
    sdb               7.41     2.00    1.48    5.06   547.46    67.40   188.21     0.31   46.80  129.57   22.66   7.51   4.91
    sdc               7.40     2.01    1.47    5.16   547.20    77.23   188.43     0.33   50.02  164.44   17.34   6.75   4.47
    sdd               7.42     1.87    1.42    4.51   546.97    45.87   199.69     0.39   65.07  211.90   18.71   7.67   4.55
    sda               7.37     1.86    1.46    4.42   546.57    36.04   198.25     0.26   43.54  122.63   17.52   7.18   4.22

OK, that's 4 7200 RPM SATA disks, definitely not SSDs. They're in RAID10, so definitely better than 1 drive, but still, all under 5% utilization.

Big builds, etc. pretty much are CPU bound, even on a quad-core i7.

That's true on my single 5400 RPM disk laptop, too (though it has a much slower CPU).

These both run Linux—maybe Windows has ineffective disk caching; I don't know. But please avoid calling people who have actually bothered to measure such things and make decisions on it "fucking idiots".

(Disclaimer: no ridiculously expensive graphics cards here)