Virtual CD performs just one task, but it does it extremely well. It creates and maintains copies of CDs and DVDs as image files on a hard disk. This means that, once a Virtual CD image is created, you can run your CD-based application directly from a faster, internal drive. The transfer rate of even a modern CD or DVD drive is considerably lower than that of a hard drive, so you notice an immediate speed improvement when running from a virtual CD.

Once installed, Virtual CD provides an easy way to create virtual drives and the CD and DVD images which run on them. The program looks very similar to a standard Windows file browser and creating a new virtual drive is as simple as right-clicking on the virtual drives folder and selecting Change Drives. The program offers a list of all available drive letters and checking the accompanying boxes creates new drives - you can have as many as you like.

Creating a new CD image is nearly as easy. Put the source CD or DVD into one of your physical drives and click on the Create button. The program checks the content of the disc and proceeds to copy it to your hard drive as an image file. Once created, you load a disc image into a virtual drive by dragging its icon across. Drag another icon across to change disc images.

The only snag you may hit when using Virtual CD is that many CD and DVD-based applications expect to find their data on the same drive they were installed from. On a multiple-disc application, therefore, you may need to make an image of the installation CD or DVD and install that from the same virtual drive on which you'll then run the data image.

Since all program code and data is now read from your hard drive, you'll notice considerable improvement in response time - Encyclopaedia Britannica completed our sample searches almost instantly, where before, when using a data CD, it had taken several seconds to come up with the same results.

All this can be accomplished with the single-user version of Virtual CD, costing £45, but the Network edition, reviewed here, enables you to serve virtual CD images to any PC on a network. We found it better to map virtual drives from the server onto drives on the client PCs, using the same drive letters. A regime of allocating the same drive letters on every client makes for fewer problems running over the network.

This clever and well-designed piece of software enables you to run CD and DVD-based applications more quickly and with fewer resources than using physical drives. Serving several machines on a network with these images is an added bonus, but it won't handle copy-protected CDs or DVDs, for obvious reasons.