These days a Lacie 160 Mb external USB2 drive costs about $125 (or less). It hardly seems worth it to roll your own.
I can't recommend a Lacie drive. I bought two of them and regretted it.
first, almost all HDDs sold in third-party enclosures are only covered by a 1 year warranty while you can get up to 5 years warranty if you buy the drive separately.
second, the Lacie (and some other companies) enclosures have hardware limits on the visible capacity of the enclosed drive, but Lacie will not tell you what that limit is unless you ask specifically, and even then they might not answer. if you buy a 160GB and later decide to replace the drive with a 400GB unit, you're out of luck because the enclosure is probably limited to 250GB.
third, one of my Lacie enclosures failed just outside of the 1 year warranty. it would have cost almost as much to get it repaired by Lacie as to buy a new one.
don't buy a Lacie. get a decent enclosure (perhaps under the guidance of one or more of the available reviews; the FireWire chip and the power supply seem to be the most important aspects of the enclosures) and get an HDD with a reasonable warranty; at least 3 years.
I'm in the process of getting a new 2.5" drive for my Hyperdrive. the Seagate (Momentus) drives all come with 5 years warranty. you'll never get that from Lacie.