let me process next clealy
after saving theme file ....!
include your custom visual style using OEM preinstall in Windows XP installtion source.
Copy your theme into
$OEM$\Resources\Themes\ ,
wallpaper into
$OEM$\Web\Wallpapers\and set
OEMPresinstall=Yes into your WINNT.SIF
Now you have to add these two lines to apply custom theme at instllation of Windows
CODE
[Shell]
CustomDefaultThemeFile = "%WinDir%\Resources\Themes\MyTheme.theme"