TrustedReviews have looked at the Seagate 160GB Portable External Hard Drive

This is where something like the Seagate Portable External Hard drive comes in. It’s a good compromise between the two, being portable yet also offering a decent capacity, with 160GB the largest size currently available. The drive inside spins at 5,400rpm, and has 8MB of cache, as you’d expect of a standard drive. There is a version available that spins at a faster 7,200rpm but that’s only available at a capacity of 100GB.

Seagate 160GB Portable External Hard Drive Review