Active@ Hard Disk Monitor is a freeware disk utility that checks and monitors the status of your hard drives to help prevent data loss. The system is based on the Self-Monitoring Analysis and Reporting Technology (S.M.A.R.T).

This software utility monitors the HDD SMART status.
For example: hard disk parameters such as Temperature, Head Flying Height and Spin-Up Time to notifies a user if critical conditions occur. Disk Monitor also displays hard disk drive information, current S.M.A.R.T. attributes and the overall status of the hard disk’s health.

Advanced disk scan allows you to detect bad sectors on a disk’s surface. The software can be launched automatically at Windows startup and monitor the system in the background. An icon in the System Tray can display the temperature for selected HDD(s).

This is a good program and it is free. Particulatly good to make sure your hard disk is not overheating on these hot summer days.
For more info and download go to http://www.ntfs.com/disk-monitor.htm