I've found a way to change different windows icons through registry but unfortunatlly i can't find a way to rebuild icon cache during the unattended installation. so if you know a way to do this please tell me

If you apply the registry hack before the GUIRunonce stage then the icons will load automatically. I do this already.

could you explain me how exactly do you do this?

Include the reghack in the cmdlines.txt file, I can't validate if this will work. I actually run my reghack file during the GUIRunonce section. So at the end when it reboots all the icons are in place.

well you could just delete IconCache.db this is found in \Documents and Settings\<username>\Local Settings\Application Data\

But you will need to reboot for it to take effect.