When a computer saves a file or document, it fits it into the gaps between other files already on the hard disk to use the available space most efficiently. In doing so, it splits the file into chunks - it ‘fragments’ it.

In the main part, this works fine. However, to reload a file, computers have to find all the bits and put them back together, which takes time and can slows things down. To combat this, 'defragmentation' stores files sequentially and whole making files easier to find, thus speeding things up.

Diskeeper has been doing this job for a number of years; there have been ten iterations before Diskeeper 2007 Pro Premier. The biggest new feature of this version is that it defragments files in the background, without having to be scheduled to run at a particular time.

It’s pretty much a ‘load and forget’ piece of software, which is a good job as manual defragmentation – still available – is horrendously slow. It took well over 24 hours to get close to sorting out a 13GB hard disk.

Invisitasking technology is what enables defragmentation to go on in the background and Diskeeper’s own resource monitor shows that it uses less than eight per cent of system resources, which is impressive and certainly won't make too much of a dent in your computer's speed.

The Invisitasking aggressiveness can be accelerated to speed up the defragmentation process but this will slow down a computer.

The other useful feature of Diskeeper (if your version of Windows is running the NTFS filing system and not FAT32), is I-FAAST. This technology learns which programs you use most and positions them on the fastest part of the hard disk during defragmentation. In the real world, we saw speed improvements of between 20 and 30 per cent when loading these programs.

The software is logical enough to use, with easy step-by-step guidance for setting up both automatic and manual defragmentation. Serious 'defraggers' can print out the results of before and after defragmentations to see where improvements have been made.

However, while Diskeeper 2007 Pro Premier does a good job, so does Windows' own Defragmenter utility and that's completely free.

Also consider
Tuneup Utilities 2007
Reasonably priced, wide-ranging tools to get your Windows PC in top condition

Diskeeper 10 Home Edition
A defrag a day keeps the disk doctor at bay

Windows Disk Defragmenter
Slow but you can schedule it and it costs nothing.

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