external hard drive vs. internal

USB 2.0 has a bus speed of 480 Mbit/s = 60 Mbyte/s, whereas ATA bus speed is 133 Mbyte/s, and SATA bus speed is 150 Mbyte/s. Compare with Ultra-3 SCSI = 160 Mbyte/s, Ultra-320 SCSI = 320 Mbyte/s, firewire = 400 Mbut/s = 50 Mbyte/s.

From here, you can see that USB 2.0 bus speed is faster than firewire, but slower than ATA, SATA and SCSI.

The link below provides comparison among them.
http://www.adaptec.com/worldwide/product/markeditorial.html?prodkey=io_comparison

As a conclusion, generally speaking, USB 2.0 could be slower.

Actual performance is much lower than the figures given above but this is true of IDE/SATA also, none of which will perform to 'spec' in the real world application.

In any case the USB would always be slower - even slower than the lower RPM unit.  If you have the option you would be farther ahead to install the higher speed drive internally and use the lower RPM for the external USB.  Even at the lower speed it will keep up with the USB connection.  This would give you a small performance boost for the system depending on the actual drives used.

If you need a good performing external drive you should look to external SATA.

Here's a link to a company that does a lot of external SATA as well as good USB enclosures,
  http://www.addonics.com/products/external_hdd/

The have a nice chart at the bottom of this page comparing interface speeds,
  http://www.addonics.com/products/external_hdd/aeehdsa35.asp

I have a western digital 160 gig hard drive which says IDE-ATA interface.  does that mean i can get a SATA enclosure?  

You need a SATA-IDE convertor for the interface to match.

do you think it would be worth the trouble to get a converter and have to fuss with the power supply for and external drive?  with the converter would it be just as fast as a regular SATA drive?   i have a laptop and my hard drive is pretty dated.  i was hoping to use this new one to speed it up.

Think of the connection from disc to computer as a pipeline, and USB, IDE, SATA, FireWire, etc. as parts of that pipeline.

The speed of the drive will never be more than the slowest part of that pipeline - an IDE->SATA converter (or SATA->IDE converter for that matter) will bring the drive down to IDE speed (or less, as each conversion takes some time too)

but IDE speed is still waay faster than usb or firewire right?

You could also get a SATA interface.

http://www.newegg.com/Product/ProductList.asp?Submit=Go&DEPA=0&type=&description=pci+sata&Category=0&minPrice=&maxPrice=&Go.x=0&Go.y=0

The speed of an external enclosure will never be as good as an internal drive simply because of the latency involved in usb communications. The rmps do have a big impact on overall performance, but I have never actually seen any comparative numbers.

wouldnt it be possible to get an IDE input for my PCMCIA slot?  or do these not exist?

Hi,

PCMCIA is very much slower than USB 2.0 and Firewire.

You didn't say this was a notebook! But there are SATA pccards:

http://www.newegg.com/Product/ProductList.asp?Submit=Go&DEPA=0&type=&description=pcmcia+sata&Category=0&minPrice=&maxPrice=&Go.x=28&Go.y=32

yea ive seen the SATA cards but im just a little confused on the wiring and power cords for the hard drive.

The site doesn't mention anything on that, but there are links to the manufacturers, which don't mention the wiring either, but I guess you could ask them there...

>> I have a western digital 160 gig hard drive which says IDE-ATA
That's just "normal" ATA, which needs a IDE/SATA converter to fit with SATA enclosures. Why are you so obsessed with SATA?

>> PCMCIA is very much slower than USB 2.0 and Firewire.
True - but PCMCIA has been off the market for ~5 years. Todays laptops have lightning fast Cardbus/PCcard slots (32 bits, backwards compatible to the 16 bit PCMCIA and usually called by that name).

Cardbus->SATA->IDE is probably your fastest option, but you will need the following:
1) a SATA enclosure
http://www.byteccusa.com/product/enclosure/ME-740S.htm or http://www.byteccusa.com/product/enclosure/ME-720S.htm
2) a SATA-> IDE converter if you want to use your current disk.
http://www.byteccusa.com/product/SATA/SATA.htm
3) a SATA Cadbus card.
http://www.newegg.com/Product/Product.asp?Item=N82E16815124012

SATA cable is included with the enclosures and PCMCIA card, but retail under $5.
I have no idea about the quality of these items - they're examples of what you need

i would prefer normal IDE compared to SATA.. as.. SATA will get hot faster... so if u r chossing a SATA hd... i recommmend u buy some cooling syste (just a normal small fan is enuf..) pointing to the SATA hd...~ mine one is doing like this.. my sata gets hot faster than my ide.. so i attached a small fan to it..~ just in case it overheat and spoit my sata hd...