http://www.macintouch.com/maxtor2.html

Checking the S.M.A.R.T. status was mentioned...but there's no free Mac utility that does this...yet.

Here is the description of SMART suite, from SourceForge.net:

SMART suite controls and monitors storage devices using the Self-Monitoring, Analysis and Reporting Technology System(S.M.A.R.T.) build into ATA and SCSI Hard Drives. This is used to check the reliability of the hard drive and predict drive failures. The suite contains two utilities, smartctl is a command line utility designed to perform simple S.M.A.R.T. tasks. And smartd is a daemon that periodically monitors smart status and reports errors to syslog.

Here's the download link:

http://telia.dl.sourceforge.net/sourceforge/smartsuite/smartsuite-2.1.tar.gz