Microsoft actually prepared a method for installing Windows XP with all
required fields ready keyed in on a txt file called winnt32.sif.
Follow the steps in the Microsoft support page to prepare the file.
Unattended Installation for Windows XP.

Windows XP Service Pack 2 Integration procedure
Create folder XDCD
Copy windows CD i386 folder into XPCD
Download Windows Xp Service pack 2
Rename the Windowsxp-kb835935-sp2-enu.exe file as Xpsp2.exe
Integrate : 
 C:\XPSP2.EXE /integrate:C:\XPCD
Extract Windows boot img from CD into XPCD
Burn CD with "Boot CD" option


SP2 integration Windows XP SP2 -Microsoft method :
Part1

Part2

Part3

Part4