I have a generic (CompUSA branded, made by FMI) USB 2.0 and Firewire enclosure that uses the Prolific PL3507 chipset. It seems to do okay with smaller (<120 GB) drives, but today I tried it with a brand new Seagate 160 GB drive and couldn't initialize it with Disk Utility (in 10.3.5, even tried OS 9). There is almost no information on this chipset out there, except for a few blogs and forum posts from (mostly) Linux users who seem to have problems with it as well.
Disk Utility will see it as a 149 GB drive but won't initalize or partition it--whatever changes I make are not saved, and it reverts to the standard Unix volume name (d2s10 etc.)
Any ideas? I even tried this on an XP box (using the USB 2 interface) and couldn't get it to recognize the drive either.