• Over time, files accumulate on your hard drive and become fragmented---a single file can be all over the disk. Disk defragmentation increases system performance and extends the hard drive lifespan by reassembling these files in one continuous place. Also, cleaning up unneeded files before defragmenting reduces the number of files the defragmenter must handle, reducing the defragmentation time. Defragmentation should be done once a month when the computer is not used.
  
  

Disk Cleanup

• Built into Windows, the Disk Cleanup tool (found under Accessories/System Tools) cleans Windows-related temporary files, Internet Explorer files, downloaded installation files and the Recycle Bin. Disk Cleanup can also uninstall Windows components and programs as well as delete System Restore points. The restore point cleanup deletes all but the most recent restore points in one step. Disk cleanup does not clean third-party program temporary files and is not customizable.
  
  

Disk Defragmenter

• Also found in the System Tools folder, Disk Defragmenter is a rudimentary disk defragmenter. It only defragments the C:\ drive and cannot defragment system files. It starts the defragmentation over if the disk is accessed. It has very slow performance.
  
  

SysInternals PageDefrag

• PageDefrag defragments the system files that are in use during the next reboot. PageDefrag provides fragmentation information of the registry files, the hibernation file (where memory is dumped during hibernation) and the Windows swap file (the virtual memory file). PageDefrag handles the system files before they are in actual use, and before other computer programs activate; therefore, it is quick. It is best to run PageDefrag after all other files are defragmented.
  
  

Piriform CCleaner

• CCleaner is the mother lode of disk cleaning utilities. It cleans temporary files and histories left behind by hundreds of programs; it cleans files left behind by Internet Explorer, Firefox, Safari, and other major web browsers; and it cleans invalid registry entries, the Recycle Bin, and Windows Update backup files as well.
  
  CCleaner cleans old system restore points; however, it only cleans one restore point at a time. It cleans custom files, folders and registry entries and has advanced configurations to add other programs.
  
  CCleaner Enhancer, a companion program for CCleaner, adds extra programs and applications to CCleaner's advanced configurations. Both programs are updated regularly. Both programs are free for personal and commercial use. They work with Windows 2000, XP, 2003, Vista and Windows 7.
  
  

Piriform Defraggler

• Also by Piriform, Defraggler is free for personal and commercial use. It works with Windows XP, Vista and Windows 7. Defraggler works faster than Windows Defragmenter, with options to defragment single files and folders or the entire disk. It has options to clean and check the disk for errors prior to defragmenting. It defragments some files that are in use by the system. Defraggler also permits shutdown after defragmentation. It only defragments one drive at a time.
  
  

Auslogics Disk Defrag

• Auslogics Disk Defrag has the features of Defraggler, but it can defragment more than one drive at a time. It works with Windows Vista, XP, Windows 7 and 2003. Disk Defrag is free for home use or $19.95 for business use, as of 2010.