Back in the old days, if a Macintosh computer crashed, certain files would be damaged, and that would be it. All of the data on the drive would be lost, which was a serious setback if one had not diligently backed up files. Total data loss is still a risk today, even though the latest operating system, Mac OS X, rarely crashes. The biggest causes are defective or low-quality hard drives. The tried-and-true solution is still to back up data regularly to media that can be stored offsite from the main computer. I find, based on my experience working for a small publishing company, that the most common data losses come from people who are in an editing frenzy and not from hard-drive crashes. Here are common examples: Employee No 1 opens proposal A, and edits it for another client. Six months later, he wants to know if I have a copy of the original proposal. Employee No 2 deletes all her e-mails regularly after two months, on the assumption that I keep copies on the server. This is fine - until she requires a year-old e-mail that ended up being a contract for a price, according to the customer. Employee No 3 creates a new database from what she thought was a copy. When she deleted what she thought was another copy, it turned out it was the only version of the file. Employee No 4 gets fired; she downloads a Zip disk full of client information and deletes those files on the company's server before she leaves, assuming the company will back up the modified version. Employee No 4 also copies and deletes the administrator's serial number database so she can sell the software licences to friends. Three of the above scenarios actually happened, while the fourth is hypothetical. But what they all have in common is the fact that if you make an exact copy of your files and then simply update them each week, you will be out of luck replacing the missing files, as demonstrated in the above examples. What you need is an 'incremental' backup program, which is what shareware backup applications do. They back up fully once, and then synchronise each week, bringing data up to their existing state. A software product called Retrospect has been traditionally employed by Mac users to do what is known as 'evolutive' backup, in which each version of a modified file is saved. It can also save these files to tape drives. But for peace of mind, there are less expensive, less complex Mac tools available from Prosoft Engineering ( www.prosoft.com ). Prosoft used to make custom software for Apple and other large companies that wanted high-quality, dependable applications. The company built Apple's Disk Burn, Password Protection and Drive Setup applications. Last January, however, Prosoft entered the consumer market with an eye to supplying easier-to-use and better data recovery applications than are now available. Data Backup X, their first consumer product, was an instant hit. Priced at US$49, it backed up a network or a disk simply and reliably. It also does not cost an extra US$150 for every five machines on a network like competing products do. Data Backup X unfolds via two buttons and an arrow. One button says Backup and the other Restore. Click either and it will walk you through the steps. The arrow is labelled Advanced Actions, and when pressed it reveals three more buttons - Copy, Synchronise and Compress - and a simplified scripting/automation set-up. The program is easy to customise, so you can do an incremental, evolutive, or any type of data backup you fancy. Data Backup's only failing is that it does not back up to tape drives. But it is incredibly fast, and you can get plenty of backups on the new large FireWire-standard hard drives just released. I recently tested a 320-gigabyte FireWire hard drive from Other World Computing (US$459 compared with a Mac-compatible tape drive at US$1,500). A 60GB incremental backup took only 12 minutes. Using a tape drive would have taken hours. If you forgot to back up and your hard drive is toast, Prosoft has a cure for that as well. Its US$89 Data Rescue product recovers lost data that other popular disk repair tools give up on. It will even recover lost data when your computer or other disk utilities cannot find the damaged disk. It needs only a transfer disk for the saved data. Prosoft also makes a cool tool that recovers files you deleted a few weeks ago, even if you never do backups. This product is called Data Recycler. Every time you or your Mac deletes something, Data Recycler saves a hidden compressed copy. You can decide on the number of files you want, and the length of time you want them saved, and it will automatically make adjustments. All three Prosoft applications are available for a package price of US$149. E-mail Dave Horrigan at email@example.com with your Mac queries.