For years, I have used Microsoft's defrag utility, but recently started using Norton Systemwork's SPEED DISK. I just optimized my C disk with Norton, but then when I analyzed the disk in Microsoft's Disk Defragmenter, there appeared to be huge amounts of files needing defragging. Is optimization a different process than defragging? If not, why do so many files seem to need defragging after being optimized? (other than the potentially obvious reason that SPEED DISK does a bad job...) Thanks for your help.

I would stay with MS defrag in that case. I really don't trust certain products.

I don't know the answer to your question. However, I would point out that optimization and DE-fragmentation are not the same thing. Defrag unifies files that may be scattered all over the disk. Optimization places certain files on specific areas of the disk to "optimize". Perhaps MS and Symantec have different approaches to this.

Can-O-Worms. OtheHill pretty well nailed the difference between the two. If you are running Norton Systemworks, installed, and using its features you might be better off with Speed Disk. If the choice is only betweem M$ Defrag and Speed Disk, it depends on which works best for you. Systemworks can be a resource Hog, not to mention a major distraction to daily Computing. Monitors too may parameters and, IMO, fails to live-up to promises of preventing System Crashes. Speed disk by itself, not so bad. At least on Win98SE. Haven't tried on XP. What you see in M$ Defrag Analyze, after running Speed Disk, is the difference between the two. Not one doing a poor Job, just a Different job. You would have to delve into how each does what it does and why, then decide which theory make the most sense to you. There is nothing to learn from someone who already agrees with you.