Not really. Take a look at the Icy Box series. Just take the hard drive out, open up the Icy Box, put in the connectors, and you have an external USB2/Firewire hard drive
Why, do you have a 2.5" laptop hard drive or something. It all depends on the holding mechnaism inside really. A normal desktop hard drive is 3.5", and a laptop is 2.5".