HDD Observer is a powerful monitoring and repairing tool for your hard drives.

If HDD temperature is near its critical value then HDD Observer begins to check it more frequently to exactly detect the time when the temperature will reach it's critical value. Evident - if critical value is reached, then HDD Observer will check HDDs with a lower frequency to release any system resources.
Another interesting feature is 'System Fragmentation Monitoring':
HDD Observer begins fragmentation check only when computer is idle, and all system resources are free.
In this case HDD Observer will check for fragmentation until will finish or the user will need any system resources. After check it informs the user about fragmentation level and can even defragment HD using its build-in defragmentation tools.

Features:
· Monitor hard drives health, performance and temperature 
· Monitor hard drives activity and show it in a system tray icon 
· Check file system fragmentation and registry fragmentation 
· Defragment file system and registry 
· Automatically and real-time find and remove un-needed files and registry values 
· Windows XP/2003/Vista compatible
· Native 64 bit support for best performance
· Low memory usage

Download: HDD Observer 3.4.2 (13.6 MB) | Screenshots | Homepage