HardcoreWare.com has an in-depth performance comparison of XP SP1 vs. SP2. It's a 7 pages long and covers a wide range of tests.
The bottom line...
After looking at the results, one thing is certain: You have more to gain than you to to lose by installing SP2. Performance is for the most part identical to SP1, except in a few cases. In those cases, SP2 was actually faster!
Not that this'll keep the skeptics quiet, but at least it's more ammo for the folks that use reason and common sense to make decisions.
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