External USB drive boxes should be readily available, but there are several choices and you have to get the right one for the drive you have.

Hard drives come in two physical sizes, nominally the "desktop" size (3.5") and the "laptop" size (2.5"). Since you don't really have to put the lid on to run a drive "externally," the physical size of the box isn't too important, but the two sizes of hard drives have different sizes of connectors, so you do have to get the right box size in order to connect to the hard drive.

The most common boxes come with an internal interface for eitherIDE or SATA hard drives, and the box you get must match the drive you want to put in it.

Since the computer only sees a USB plug, and the hard drive only sees the internal side of the interface board in the box, there should be no "setup" or "compatibility" problems if you get the right box for your drive.

Boxes are also available with EIDE/SATA interfaces built in, at roughly twice the price, with separate internal connectors for the two kinds of hard drives, so you can put either kind of 3.5" drive in a 3.5" EIDE/SATA box, or either kind of 2.5" drive in a 2.5" EIDE/SATA box, just by using the correct one of the two internal connectors and leaving the other connector hanging loose.

The biggest problem with using an "internal" HD in an external box is that the boxes tend not to be well cooled, and the drives may die prematurely due to heat exhaustion; and the smaller mass of an external drive makes it much more sensitive to bumps and bangs if the drive isn't glued down to a desktop or other heavy object.

Generally, 2.5" drives are more rugged than 3.5" ones, since they're designed for use in laptops or other "portable" devices, but omission of the "ruggedizing" is largely what makes the larger drives as much as 10x as fast as the little ones in actual working speed, for drives with the same "published specs." In an external box, the drive speed genrally makes less difference than in an internal drive use, since the USB interface speed is nearly always slower than either kind of drive.

Everybody should have at least one box, since it's the simplest way of transferring stuff from the drive you take out of a dead computer to the drive in a new computer, but drives in boxes, especially desktop drives, have very low survival if they're ever moved for any reason, even if you're very careful about making sure the disk isn't moving when the box is picked up. I have two such running after a couple of years, but have seen about 5 "killed" in a few months after being put in boxes. The ones that died were "used" when they went into the boxes, but I still consider their failures "premature."

Get a box if you need to transfer anything from the old drive to a computer. If you really need an external drive for space reasons, blow the <$100 (US) for a 500 or 750 GB portable external USB drive. Unless you store a significant amount of Video, or a whole lot of audio, on your computer, the 1 TB drive is just more to lose when that drive fails. Get two of whatever you choose, and keep dual backup copies(?) if you really have anything valuable.

John