I have several ready made external 3.5" USB drives. All of mine get power from an AC transformer. I have 2.5" units that get all their power through two USB cables. I don't know what the ready-made ones look like on the inside, but you can buy a standard drive and mount it in an external USB case, then it would fit for sure.

Another option I've used, if it suits your needs, is to use standard hard drives and this USB adapter which works with SATA or IDE, 3.5" or 2.5" and comes with a neoprene sleeve to protect the drives. They work well and the drive can be stored in less space. 

http://www.newegg.com/Product/Product.aspx?Item=N82E16812119152 

-----Original Message-----
>From: Dean Kukral <[log in to unmask]>
>Sent: Aug 31, 2009 11:04 AM
>To: [log in to unmask]
>Subject: [PCBUILD] External "hard drive" internal drive properties?
>
>Can the actual hard drive in an "external hard drive" such as a WD Passport be removed and placed in a desktop?
>
>Do they have a standard SATA (or IDE) interface?
>
>What kind of power connection do they have, SATA, Molex, or ?
>
>I am not concerned if they will physically fit in a desktop, only if they use standard connections.  I am mainly wondering if the 
>extra circuitry on one goes bad, can you remove the hard drive from the case and use it in a desktop and/or recover data from it on 
>the desktop.
>
>Out of curiosity, are these made for low power?  It seems like hard drives take a lot of power (at least my Raptors do) and a USB interface would be a little short.
>
>TIA, D. Kukral 

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