I reported earlier that apparently, pirated XP Keys appear to be working with SP2 Final Build 2180! Here's a reply MSFN got from Gary Schare at Microsoft.

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Many users have questioned why illegal PIDs are being allowed on a Windows XP SP2 installation when they were blocked in previous betas. This is due to Microsoft's new approach on security in Service Pack 2 to prevent any further Windows XP machines from getting infected with viruses and malicious attacks. Microsoft's Gary Schare answers:

Microsoft clears up confusion regarding illegal PIDs in XP SP2