I have moved from a PC to the iMac. In the Windows environment, I felt a need to run utilities to clean out the registry and defragment the hard disk frequently. Is this also needed on the iMac? If so, what programs are recommended?

The Mac operating system, called OS X Leopard, doesn’t include a registry, which is a feature of Windows that holds information that programs need to operate properly. So there’s no need to clean or maintain any registry on a Mac.

Mac hard disks, like those on Microsoft (MSFT) Windows computers, can get fragmented — a condition in which parts of files are so scattered around on the disk that the disk runs slowly. However, the operating system has some under-the-covers features that generally obviate the need to run a defragmentation utility. In fact, Apple (AAPL), which calls defragmenting a disk “optimizing” it, flatly claims that “You probably won’t need to optimize at all if you use Mac OS X.” There are some Mac defragmentation utilities, but I don’t believe you will need them unless you have large numbers of extremely large files and almost no free disk space.

My son’s computer frequently gets infected with adware, pop-ups. Recently it was hit with a continuing pop-up ad called VirusHeat that touted itself as a solution to the computer’s problems. When I paid for VirusHeat, the problems went away. Is it legitimate?

According to numerous reports on the Web, including some from security companies, VirusHeat is a form of malicious or misleading software. It falls into a category that attempts to scare people into thinking their computers are badly infected, or exaggerates any problems you may have. This is a common tactic now used by creators of malware.

Some of these fake or misleading “security programs” may be designed merely to make you pay. Others may even be designed to install the very kinds of viruses, spyware or adware that they claim to fight.

I have updated to a new PC. My data are on a floppy disc. There is no floppy disc drive on this new computer. How can I transfer my data?

For around $25, you can buy an external floppy disk drive that plugs into a new PC using its standard USB port. If you do so, and connect it to the new PC, you should be able to copy your data to the new computer’s hard disk.

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