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[hit_ny]

USB 2 has a burst performance of 400kb/s

Internal HDs with PCI is 133kbs with SATA-1 going to 150kbs

Does this mean that an external HD via USB2 will give better performance (than internal HD) with MC ?

[JimH]

I wish.  I'm a software person, but I think the drive speeds are MB/sec.   

[jgreen]

In college I was an English Major (too many years ago to mention).  While there's no doubt that this education gave me the fine-tuned ability to correct everyone else's grammar at cocktail parties, there was a hidden advantage, also.  You see, majoring in English made me fit for virtually no important job in the world.  Therefore I have plenty of free time on my hands to read the specs printed on the packaging for computer products.  Through this lengthy course of study I have learned:

1.  Transfer specs for USB and firewire are quoted in Megabits, eight of which equal a megabyte.  Don't ask me why; an English Major is not expected to know this.

2. The burst speed of USB 2.0 is actually 480 megabits per second.  Divide that by eight and you have megabytes.  On paper, 60 mb per second, burst.  Not to worry, though, this spec was written by a bunch of liars, IMO.   

3.  Drive speeds are quoted in megabytes per second, just to be difficult, I guess.  The equivalent xfer speed of SATA-1 is 150 megabytes per second.  Similarly, SATA-2 is 300 mb per second.  This compares, I believe, to ATA xfer speed of  100 mb per second.

4.  Bus speed comes into play here, and no one will tell me this in plain english (grammatically correct or otherwise).  But suffice it to say, bus speeds and traffic mean that you will never see anything close to this with PCI.  PCI-x is better, and PCI-ex will be in a class by itself, once fully implemented in 16 lanes.  By that time SATA-3 will be out, with 600 MB per second specs. 

I reserve the right to have mangled this "data" thoroughly, via poetic license, hyperbole, flashback, etc.  Decimal places and conversions are of particular concern for me, and this post is rife with them, so beware.

[Myron]

The standard is to use upper case for bytes (B) and lower case for bits (b).  This is very often ignored, unknown, misused, whatever.

At the end of the day, the actual data transfer rate of any disk is limited by rotational speed and aerial density.  You can't go any faster than this for long data transfers.

[hit_ny]

Ahh forgot about the MB for PCI..

so PCI 100 is 800kb/s

that's still twice as good as USB2 and PCI can actually sustain that better vs USB2..notwithstanding traffic etc.

..which explain's why even low-end internal (PCI 100) is still better than USB2.