I use a $9 USB 2.0 external laptop hard drive enclosure, and it has worked great so far on a number of hard drives, for copying/backing up data and performing general cleanup on laptop hard drives.
Though, if you work with older laptop hard drives (like the under 10.Gig kind), many are thicker than the newer laptop hard drives, so you need a case that can fit thicker hard drives.
Some laptop drive enclosures slide the drive in from the end, and therefore don't fit the thicker drives. The one I have, the drive goes in from the top, so I just leave the lid off for thicker drives.
They also have USB adapters with no enclosure, but mine has worked fine, and I like having the circuit board of the hard drive protected.
One more thing to pay attention to is that some laptops use an adapter attached to the laptop hard drive connector and it's sometimes hard to tell that it is an adapter, since it fits so perfectly. So if the hard drive connector doesn't seem to match the laptop drive enclosure connector, you have to remove the adapter to connect it to the enclosure.
- Eric,
http://www.InvisibleRobot.com/ 
