defragmenting the HDD in OS X

good to hear that.
so can you tell me what are the things to look out for as far as regular maintenance of the HDD and the filing system is concerned?
i've heard that unlike windows the mac OS does not need formatting. even after 3 years? does this mean that there is no maintenance of any kind?

e.g. if i keep moving a file(s) around from one folder to another doesn't this eventually slow down the OS?
basically i am curious as to the factors (besides wearing out of the HDD) that will eventually cause the system to slow down.

interesting that you say macs will eventually need AV - why so? because the market is growing faster and someone or the other will start making viruses?

This is another myth that hasn't really been true for over a decade on Windows or a Mac.

Windows, and Mac OS X, run a number of routine maintenance programs automatically and without the need for any kind of user intervention. Windows has been doing this on the NT side of things for years, and when XP came along, moving everyone onto the NT platform, it became a standard function of all Windows versions. Mac OS X, being based on FreeBSD (a Unix derivative) also has a series of programs that run in the background that keep things tidy. Apple actually went out of their way to make it difficult for the user to mess with these functions. They even threw in Automater to try and discourage people from using the lower level Unix tools to do much the same thing.

Windows and Mac OS X have been largely maintenance free for the past decade, but you have a few people who are still living in the world of 20+ years ago who keep these myths alive. All those registry programs and everything else on Windows are completely pointless, and usually end up doing more harm than anything else.

There are three things which affect system performance, and it doesn't matter what the OS is. Until someone comes up with a radical new design for computers, these will remain constant.

1: CPU speed
2: Amount of RAM
3: Number of running programs

Those three things account for probably 95% of ANY computer's performance. Mac, PC, even smart phones and tablets. You want to speed up a computer, you increase the first two and decrease the third.

And since you mention moving files around, I'll just burst another myth bubble. The idea that you need to keep some percentage of the total HDD free to ensure good performance is a complete load of crap. The only thing you need to make sure of, is you have enough free space for the swap file. On systems with anywhere from 2-8GB of RAM being pretty commonplace, this is really of very little concern. Back before RAM and disk space became so plentiful, people might suggest leaving 10% of your HDD free for swap use. Which made a lot more sense when 10% of your drive might only be 100MB give or take. But with 1-2TB drives becoming far more common, I have yet to see a convincing reason why someone should idle 100-200GB of their drive for swap space. It just gets back to the notion of people living in the world of 20 years ago. The average person with 2-4GB of RAM in their system is unlikely to ever need more than about 100MB of swap space. So if you want to be on the really safe side, you could set aside say 500MB. If you ever need even that much, you probably need to think about upgrading your hardware.

Just to bottom line all of this. Macs and PCs are largely maintenance free. Have been for years. Most of the "maintenance" tools out there are scams that just prove P.B. Barnum right when he said there was a sucker born every minute. Don't be the next one. Computers do not get slower over time, our expectations for them grow. As we use a computer more, our baseline expectation adjusts to the new computer. Say you have a pretty run of the mill baseline Core i3 iMac, which you set aside for a week in order to use a G3 iBook, by the time you go back to using the iMac, it will seem like a brand new computer again. Even if the thing has been turned off all week, and nothing about it has changed. WE are the ones who change, not the computer.

And no, I say that Macs will need an AV program sooner or later because sooner or later someone will figure out an effective way to launch cross platform attacks. And sooner or later Microsoft will stop being the low hanging fruit it has been since the early 90s. Market share has little, if anything, to do with the number of threats. If it were market share driving things, then the meteoric rise in popularity of both Mac OS X and Linux should have seen an explosion in new threats for both platforms, yet they remain largely flat. Truth is, there are very few true hackers out there. Most of the people we think of as hackers are just social malcontents living in their parents' basements. They probably have less overall technical skill than you, and rely completely upon a program that automates the whole process for them. A few mouse clicks and the program starts scanning computers for a list of known vulnerabilities, and then proceeds to exploit any that it may find. Without this program, these people would be completely helpless. There also has to be something to exploit. Right now, Microsoft makes for a very easy target. Internet Explorer's ActiveX system is better than anything these kinds of people could have come up with in their wettest of wet dreams. Microsoft developed it in the age of innocence on the Internet, and really allowed the age of malware to be born. With Microsoft, usability trumps security each and every time, and ActiveX was intended to be highly functional, not so much highly secure. Before ActiveX, there was no real effective way to remotely execute code on another person's computer on a large scale. Then Microsoft comes along, with a system that lets you boobytrap a website with a little bit of malicious code, and voila, instant and complete access to someone's computer. Ever since ActiveX showed up in IE3, Microsoft has been unwilling to properly contain ActiveX, and been employing a number of stopgap measures. No other browser has anything like ActiveX (Google Chrome may at some point soon, but it seems Google has learned from Microsoft's mistakes), and no other browser has anything even remotely coming close to the malware problem IE has.

Assuming, one day, Microsoft finally breaks down and rewrites ActiveX in a more secure fashion, then these people will have to start looking elsewhere. Some of them will inevitably turn their attention to Mac OS X. And considering the number of people who have Adobe Flash installed, and Adobe being something of the next Microsoft when it comes to security (look at the number of issues Adobe Acrobat has had), it may well be possible to have a platform by which someone can attack Mac OS X, Linux, and Windows all at the same time. That day will inevitably come, but exactly when is the question that no one knows the answer to.

Anyway, again, the moral of the story here again is that you've had your head filled with a lot of outmoded advice. Stuff that hasn't applied for at least the last decade, probably longer. Windows and Mac OS X do not need you to run a bunch of maintenance programs. They haven't for years.