computer starts up," or words to that effect.) Find this disc now. (I'll wait while you root through your attic or basement to find it hidden in the bottom of a box somewhere.)
Back already? Super. You have in your hands a very special program. Apple Hardware Test can run only when you start up from the CD or DVD it came on; don't bother trying to copy it to your hard disk. This program performs a series of diagnostic tests on your Mac's hardware, including the AirPort card, logic board, hard drive, RAM, modem, and video RAM. It doesn't repair anything, and it doesn't look for problems such as directory errors that are the province of Disk Utility (described in the next section). But it can identify subtle hardware defects that could later lead to serious problems. Whether your Mac is fresh out of the box or years old, you owe it to yourself to make sure its major components are in good health, and this is the easiest (and cheapest) way to do so.

Note

Apple Hardware Test isn't the only tool that can check your RAM. Among the other utilities that can do this are TechTool Pro (www.micromat.com; $98) and Rember (www.kelleycomputing.net/rember/; free). I've personally had bad RAM that Apple Hardware Test could identify while these others could not, whereas other Take Control authors have had the opposite experience. Your mileage may vary!

To run Apple Hardware Test, follow these steps:

I recommend running the test again after installing RAM or any other new hardware inside your computer, or if you begin to have inexplicable problems that ordinary disk utilities do not solve.

Be Sure You Have Enough RAM

The most important thing you can do to speed up your Mac and reduce crashes is to be sure it contains enough RAM. Few new Macs ship with what I consider "enough." Even though Mac OS X and most applications can run in as little as 512 MB, in my experience performance degrades quickly with that amount of RAM when you have numerous applications and windows open at once.
How much RAM should you have? The answer depends on the type of Mac, the way you work, and your budget. On the one hand, I think everyone should have at least 1 GB (or the maximum their machine supports, if less). On the other hand, more isn't necessarily better. For example, only a few people running the most memory-intensive applications would benefit from putting the maximum of 16 GB in a Power Mac G5.

Disk Utility looks for common errors and repairs them if possible. Ordinarily, it displays a message saying that repairs were completed or that no repairs were necessary. In the (rare) event that Disk Utility encounters a serious problem it cannot solve, you may need to use a commercial repair tool such as DiskWarrior (www.alsoft.com; $80).

Make Sure Scheduled Maintenance Tasks Run

Mac OS X includes a tiny Unix utility called periodic whose purpose is to perform a variety of cleanup tasks, such as deleting old log files that would otherwise take up unnecessary space on your disk and updating the index that the Unix locate command uses to find files in the Terminal utility. The periodic utility can perform any of three sets of tasks. Once a day, periodic is supposed to run "daily" tasks; once a week, "weekly" tasks; and once a month, "monthly" tasks. (These names are more or less arbitrary; if, for example, you ran the monthly tasks every week, no harm would result.)
The periodic program doesn't launch itself, though; running it at the proper times is the job of another program, called launchd (under Tiger; in earlier versions of Mac OS X a utility called cron told periodic when to run). Apple set the launchers to run the periodic scripts in the middle of the night, so that they wouldn't slow down other things your Mac might be doing. The problem is that if your Mac happens to be off or asleep at the scheduled time (as it is for most of us), the scripts can't run. Tiger's launchd utility was supposed to be smart enough to notice that it had missed a scheduled task and run it the next time your Mac became active. Unfortunately, as of Mac OS X 10.4.4, launchd is flaky: sometimes the periodic scripts run (though possibly at completely unpredictable times) and sometimes they don't.
Tip
To learn more about launchd, which is quite useful despite its limitations, see an article I wrote for Macworld magazine: "Launch Your Mac" at www.macworld.com/2006/01/secrets/februarygeekfactor/.

In short, unless you leave your Macintosh on and awake all the time, the periodic command needs a bit of help to do its thing. The easiest solution is to download any of several programs that enable you to run the maintenance scripts manually at any time or, in some cases, to schedule them for times you know your Mac will be available. Try one of these:

• Anacron: This free utility runs the maintenance scripts whenever they're overdue, with no user intervention required. You can find it at http://members.cox.net/18james/anacron-tiger.html.
• Cocktail: Cocktail (www.maintain.se/cocktail/; $15), provides a single, simple interface for performing a wide range of maintenance tasks, including running the maintenance scripts, deleting cache files and old logs, adjusting hidden Finder, Dock, Safari, and Exposé settings, and more. Some tasks can run on a recurring schedule.
• Mac HelpMate: This utility (www.macworkshops.com/machelpmate/; free, donations accepted) can run the maintenance scripts manually or on a schedule. It also deletes various caches, adjusts hidden Finder and Dock settings, displays your drives' S.M.A.R.T. status disk usage and system uptime, and performs numerous other maintenance tasks.

• MacJanitor: If you want nothing more than a simple utility that lets you run the daily, weekly, and monthly maintenance scripts manually, the free MacJanitor (http://personalpages.tds.net/%7ebrian_hill/macjanitor.html) does that nicely.
• MainMenu: Like most of the other utilities in this list, MainMenu (www.santasw.com; free, donations accepted) performs a wide variety of functions, including running the maintenance scripts, clearing caches, and deleting log files. Unlike the others, it puts all these commands into a single, always-accessible menu, so that you can run any of them with a single click.
• OnyX: Another multipurpose utility, the free OnyX can run the maintenance scripts manually (but not on a schedule), delete various caches and log files, adjust hidden Finder, Dock, and Safari settings, display log files, run Unix commands, and display disk usage and system uptime, among other tasks (www.titanium.free.fr/pgs/english.html).

Warning! The utilities I list here are among dozens of tools that provide a pretty GUI wrapper to Unix commands. With all such programs, you should be careful not to click buttons blindly; because Unix commands can theoretically do just about anything, you could cause damage if you don't know what you're doing.

Install Antivirus Software

If this article were about PC maintenance, one of the first steps would have been to install antivirus software. For Windows users, malicious software (or malware) has become epidemic in recent years, leading to untold grief and loss of time, money, and data. Among the varieties of malware are viruses (and their close cousins worms and Trojan horses), spyware (programs that spy on your computer usage, collecting sensitive personal data), and pop-up ad programs. Luckily, very little malware runs on Mac OS X: as of the time I wrote this, I could count on one hand the programs of this sort that have been found "in the wild."
Even though Mac users have been fortunate so far, we would be wrong to assume our computers are immune to infection. Sooner or later, someone is bound to come up with malicious software that does serious damage to Macs, and when that happens, those with enough foresight to have installed antivirus software will be much more likely to continue merrily with their work while the rest of us struggle to restore our systems.

Furthermore, many kinds of malware spread via email, so you could unwittingly serve as a carrier by forwarding messages containing viruses to your Windows-using friends.
Your best defense is to load antivirus softwareand keep it up to date. Developers release regular updates (to handle the latest threats), and you must be certain to configure your preferences to download them automatically as soon as they appear.

Note

Although having antivirus software is better than not having it, and having up-to-date antivirus software is better still, there are no ironclad guarantees. A particularly wily virus might still sneak by. So you should still exercise caution, and especially avoid opening iChat or email attachments from unknown sources.

Antivirus software available for Mac OS X includes the following:

• ClamXav (www.markallan.co.uk/clamXav/; free)
• Intego VirusBarrier X4 (www.intego.com; $70)
• Norton AntiVirus (www.symantec.com; $50)