I bought an Icy Box from Scan last month. It's an excellent range of hard disk enclosures made by RaidSonic. The casing is a bit flimsy. Really, it's just two sides of aluminum that sandwich together the hard disk and circuit board. Wire mesh surrounds this sandwich and allows a large amount of air cooling. There's no fan so it's nice and quiet. That's about it.
What I like best is that the version I have (IB-351-StUS-B) supports USB 2.0 and SATA external connections. SATA is about three times faster than USB. The box even came with the SATA PCI extension bracket to install in the PC and a SATA cable. Everything you need to have a stonking fast external hard disk. If you take the hard disk somewhere and can't connect with SATA, you can always go back to USB. It's perfect.
The only mistake I made was orginally leaving the hard disk formated as a dynamic drive. It turns out Windows XP on a laptop will refuse to connect to an external dynamic drive. Dumb. External dynamic drives also need to get imported which made it a bit of a pain to tote around. I now have it reformated as a basic disk and it should make connections simpler.
Anyway, I can highly recommend picking up an Icy Box. I just need to find somewhere to buy some more SATA PCI extension brackets.