Hi,

I want to change XP boot screen prior installation(in I386 folder), so it installs with new screen already. How can I do this?

just replace ntoskrnl.exe (or its compressed cab ntoskrnl.ex_) with the propper version. http://unattended.msfn.org/advanced/hackedfiles/intro.htm should help

I've tried that method already, changes nothing

you might want to take a look at the cosmetics section of the unattended guide.

http://unattended.msfn.org/advanced/cosmetics/bootscreen.htm