>The bandwidth from the CPU to the hard drive is huge compared to the average 100Mbit LAN card. It's like being comparing a fire hydrant to your customer's garden hose.
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>New SATA drives are 3 Billion bits per second versus LAN at 100 Million bits per second. That's 30 times faster if the network isn't busy.

The speed difference is large, but generally not that large. A typical 3.5" 7200rpm drive can mechanically sustain, at best, about 50-60MB/sec (400-480Mbit/sec). Some of the newest TB-class drives with very high lineal density peak at 80-110MB/sec (640-880Mbit/sec) ( http://www.tomshardware.com/2007/11/21/samsung_overtakes_with_a_bang/page8.html ). The 3Gbit number you quote is maximum theoretical transfer speed between the drive's buffer and the host computer. This can't be sustained for more than the buffer size (typically 8 to 32MB); in the case of reading data this also assumes the buffer happens to contain the data you want, and with a typical multitasking OS this will often not be the case.

Ongoing developments in solid state hard drives will change this equation, but so will the increasingly common adoption of Gbit LAN.