In tip 5392, I described how to disable Windows File Protection for Windows 2000 SP2 and Windows XP.

NOTE: See How do I disable WFP in Windows XP SP2?

Using those same techniques for the respective operating system, you can disable WFP for Windows 2000 SP4 and Windows XP SP1a.

Windows 2000 SP4

At offset 0x62DB and 0x62DC, change 8BC6 to 9090 and save the changes.

Windows XP SP1a

at offset 0xE3BB and 0xE3BC, change 8BC6 to 9090 and save the changes.