Is Microsoft recommend to defrag WinXP or not?
and why?

Perpetual XP Argument #4 - Whether to Defrag and does it Help ?

Personal answer is yes. XP uses a process called Prefetching and
uses it's native defrag to accomplish it. Beyond that it's still a good
maintenance operation to defrag. How often depends on the level
of fragmentation on the drive. No schedule works for all systems.
If the PC hasn't had a full defrag done for a long time, you will get
some immediate performance gains by defragmenting.

Newer drives that have 8-16 Megabytes of on-board cache can
lessen the impact of fragmentation. But it still happens and does
result in slower operation.

This topic is one of those "Yes, No - Good, Bad - Matters, Does
Not" that is bound to trigger a day-long thread of points and
counterpoints.

"Mikle" <Mikle@discussions.microsoft.com> wrote in message
news:F2CD5F3F-AEF0-4093-8685-7B8400A73ACD@microsoft.com...

Mikle wrote:
No, like Solitaire, they just put the defrag utility there for your
amusement.

Seriously, you should defrag regularly, especially after installing or
uninstalling a program.

Alias

Leythos wrote:
You want to defrag:

After installing XP

After installing SP2

After installing programs of any significance like Office.

After uninstalling programs, especially big ones.

Whenever there are more than 100 fragmented files.

Alias

Leythos wrote on a day that will go down in history because we are in
agreement:

And one should disable the AV auto scan.

Alias