I myself have been wondering about 3rd party defragmenters and if they really work...I have seen many threads from others with the same questions I had... Recently I stumbled upon an online pdf version of MaximumPc online and started reading the PDF version... They actually have a section where they tested "PerfectDisk" , Diskeeper, and Auslogics against the Built in Defrag of Vista.. Looks like none of them made any increase in performance and actually slowed down the PC... Here is the link to the PDF version...The article starts on page 36... Let me know what you guys think.....

dl.maximumpc.com/Archives/MPC0608-web.pdf

There are many tests and reports showing that defragmentation helps little if improving performance.
However, they are very handy to have done whe you migrate files from one computer to another and saving data... they make those operations work more rapidly, and they reduce errors in the migration or upgrade process.
A defragmented hard drive is also a better tool for removing infestations, as defragmentation deals with compressed files and folders in a better way.
Beyond that, the worst thing about defragmentation programs is their enormous waste of your time.
We have always found it interesting that each installed defragmentation software works very differently from the others.

I have been using Diskeeper for quite a while now, and currently with version 2009 pro. I like the utility very much because it works without a problem and defrags the drives perfectly. File access is always very quick from any of the drives. I don't care what a magazine says with it's tests, I'll prefer to believe my own experience. I find Diskeeper to be head and shoulders above the default XP defragger* so I will continue to use it.

*I know that the Vista defragger is different, but after using Vista extensively for a few months with Vista, I have no faith in that OS anymore. I reverted to XP recently, and am much happier with it

I too defrag inspite of the " to do it or not to do it" and believe it does prevent things from slowing down. And another vote for Diskeeper. I've set it on automatic, works great.

Ultimate Defrag here,once a week.

I have noticed that, in my experiences, the only thing that defragmenting helps is with opening/moving files. After about 3 months of not defragmenting my fathers computer, and cleaning EVERYTHING else up, it took forever for it to "find" a folder. I defragmented, and bam, it opens immediately.

So IDK, I think it's worth defragmenting, but I usually use XP's built in defragger, but I also like the one made by the makers of CCleaner, called Defraggler.

I use dirms-s http://www.dirms.com/home/download/dirms_service.aspon my XP partition. It does a better job than the built in defragger. I sometimes use auslogic. It is good, but no noticeable difference in performance.

read how to speed up windows in the guides forum.

defragging will help in a heavily fragmented system, but you won't notice much in a newer or slightly fragmented system To speed up your system read the guide.

Hasn't this reached the end of its useful humor and good taste?
"Did I ever tell you you're one fart smeller? ... I mean smart feller?"

We have performed extensive tests on a large number of systems for an organization here, using various defragmenting programs.
There are good reasons to defragment for data security and reliability, and data recovery if it should be needed, but speed change is negligible.

word of caution: NEVER DEFRAG without first running CHKDSK /F

Chkdsk corrects disk errors, which if left as-is, would allow defrag to store good data into back sectors not a good idea, is it!