Let's see if I got this right: Microsoft requires that the subdir for the OS disk files be named C:\XP and another separate subdir named C:\SP3 be used to store the SP3 data (download). Only then can the MS command slipstream them into an updated, bootable, SP3 OS disc (which is stored in C:\XP).
If I understand you correctly, I cannot use ImgBurn to create the bootable disk that can be used to re-install XP with SP3:
a) Unless I rename the c:\XP subdir to C:\i386 or don't use ImgBurn for this task.
Thanks for your help