Programs that turn hard drives into repair disks, such as Micromat's TechTool Protogo, normally come at a princely £120 or so. This is not the case with SubRosaSoft's Das Boot, which can do many of Protogo's tricks for free.

It's very simple to use. Select a drive to copy; select a drive to copy to; select which other applications you'd like on the drive; then click a button and Das Boot will copy everything across. And we do mean everything: invisible folders, permissions and more all get transferred. When you boot from your repair drive, a special launcher program appears, giving you full access to all the applications you installed.

If you know what you're doing and your needs are small, this is all quite handy. Unlike Protogo, it doesn't reformat your drive, so all your existing data is left intact, and the drive still works as an iPod. We were able to add DiskWarrior, Data Rescue II and TechTool Pro to an iPod, install an OS based on Protogo's universal boot disk, and start up an Intel iMac and a PowerBook using the resulting disk. All the programs worked, too.

But for both the very and the less experienced, Das Boot has some severe limitations. The lack of reformatting means you can't make an incorrectly formatted drive into a universal boot option unless you do it manually: an off-the-shelf Flash drive formatted as FAT for Windows didn't even register as a destination in Das Boot. It's not OS 9 friendly. You also need to supply your own repair tools and source disk.

If you already have repair tools, and your repair needs aren't too complicated, Das Boot is a handy tool at an unbeatable price. But if you're a pro, build your repair disk yourself or look at a more powerful option.