There's no showboating where hard drive defragmenting utility Diskeeper is concerned, as it's a tool that aims as much as possible to stay out of your sight. The new 2007 edition (effectively version eleven) subscribes fully to this ethos, but acknowledges too that its work has moved on.

No longer is the hard drive 20GB in size, with mainly Office files to contend with. Now, in the era of the 300GB hard drive, with movie files that exceed 1GB in size, its job has got somewhat harder. Indeed, in the help file, the publishers argue that even a daily disk defragment may not be enough to keep a well used hard drive in shape.

Diskeeper therefore battles this trend by going about its business in a different way. And thus its big new feature is InvisiTasking. The idea behind this is that it continually monitors what your PC is up to, and when it picks up that resources are unused, it does a little bit of Diskeeper work with them. When those resources are then needed, it backs away.

The developers boast that InvisiTasking is impossible to notice, and our tests pretty much back that claim up. The theory then runs that your machine is always in good condition, because Diskeeper is always running.

It also shields what was becoming a slight problem with the application, and that's the time it takes to do its work. Defragging a hard drive is never the quickest of jobs anyway, but the aforementioned growth in disk capacity and file size hadn't helped. And while Diskeeper routinely beat the in-built Windows XP defrag tool (which itself uses Diskeeper technology) for speed, it still takes its time.

However, as the program can effectively be set to be working all the time, this isn't a huge problem. There's also the I-FAAST option in the Pro Premier version, which tries - and succeeds - to speed up file access and creation. You'll need an NTFS-formatted drive to make this work, though.

Ultimately, the program does do its job extremely well. While Diskeeper 2007 happily provides quite a wealth of options, monitoring tools and reports, it's the kind of application that prides itself on needing to be set up only once, then being happy to let you forget that it even exists.

This version discourages you from the scheduling way of working of old, instead encouraging you to continually run the application, and over a period of time this did improve the performance of our trusty desktop PC and less trusty laptop. Which, realistically, is why you'd need to spend money on it in the first place.

An excellent background utility, and one that's enjoyed some useful improvements since we last met. There's a cheaper home edition available too.