I agree with Brian:
Some defraggers, such as the one in XP, are so slow as to take more time than one might save. OTOH, there are third party defrag programs that are fast enough to be no problem, and I have always noticed improved quickness after a _major_ defrag. Maintenance defrags take little time, and don't _seem_ to improve things. It is a case of keeping one's engine tuned up to like new performance _all_ the time, or letting it get so out of tune that it seems 'better than new' after an erstwhile tune-up.
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