Each week I receive a number of letters from readers asking me to expand on a previous column or explain how my comments might apply to their special circumstances. Logistics demand that I keep the length of my column to something that can be published in a newspaper, but it is not always easy. Some of the subjects I write about could easily fill a book if I were to examine all the appropriate nuances. I have selected a few letters that typify the responses and or questions I have received on recent columns because some of the questions are important to the subject and the odds are that you will find the information useful. My recent column on an ideal backup regimen ('No need for SOS calls with a simple backup plan to secure data', September 13) ) led to several letters inquiring about other applications I have previously recommended. Reader Eric Spain noted: 'I have been using Carbon Copy Cloner for cloning my hard drive to an external disc and Folder Synchronizer X for daily back-ups. You did not mention these in your column. Have you found anything wrong with them?' The answer is yes. I did not mention Carbon Copy Cloner because there are numerous reports that it does not produce accurate clones. If your main drive has 40 gig of content and your 'identical' clone has only 35 gig, that is a big discrepancy. As for Folder Synchronizer, it reportedly alters the source drive by changing permissions, something it should not do for security reasons. For what is essentially a security software utility, this is a serious faux pas. So although I have reviewed both of these apps in the past and found them to be excellent for their intended purposes, they have recently become unreliable. This is mainly because of the complexity of what they need to do, along with the constant changes in the Apple operating system over the past few years. I expect that they will both be back in the running again once they get these bugs fixed. Reader Robert Stevenson writes on an innovative way to help out a new Mac owner. He says that, '... after 10 years of painstaking study, my 83-year-old mother, who lives near Oxford, finally reached a level of competence with her 386 PC that enabled her to receive and open an e-mail, and type and print a word document. Recently, my helpful sister decided that it was time my mother gave up her old machine and installed a Power Book running OSX Tiger. This has set her productivity back more than a little. But rather than wait another 10 years before she can view the pictures of her grandchildren and reply to e-mail, I have been searching for a way to operate her machine from Hong Kong. 'I have looked at Apple Remote Desktop 2 and realise it is primarily meant for system administrators networked on a LAN. But if I install it on my G5 running OSX Panther in Hong Kong, will I be able to view her screen in Britain and help her with opening files and organising documents? Do you think this is an appropriate software solution or are there others I could use?' Apple Remote Desktop will do the job but you might want to check out Timbuktu Pro ( www.netopia.com/software/products/tb2/mac/index.html ). It is about half the price and offers voice intercom as well as instant messaging. It is highly regarded among administrators and reportedly just as easy to install and operate as Apple Remote Desktop. Reader David Tan typifies the questions people have when they make the big switch. He says: 'I finally made the switch to the Apple after many years as a Windows user, and I am now the proud owner of a new iBook. However, I'm finding the transition difficult. Do you have any recommendations for sources I can find on the Web or in magazines that can provide me with good summarised information that will help me make the transition quicker? In particular, I would like help on key differences in OS features, and popular productivity software (shareware and paid).' I recommended Mr Tan go to www.versiontracker.com for software (including paid and free). You will find most of your Windows favourites there in Mac form. They have a reader rating/review system that can help you decide on what to use. My favourite magazine for Mac education/orientation is MacAddict with MacWorld magazine a close second. The book Switching to Mac: The Missing Manual by David Pogue, is great for orientation and basic differences. It is available through Amazon.com. The Mac Help in the centre of the Menu Bar has all the instant help you need and a searchable help application for whatever application you have running. The Help applications also contain the application-specific shortcuts and tips. If all this does not help, you are always welcome to drop me an e-mail. E-mail Dave Horrigan at firstname.lastname@example.org with your Mac queries.