Logon and boot screens provide the finishing touches to a Windows XP skin. But what are these interface elements, and how do they work?
A logon screen appears when you log on to Windows. The same logon image also appears when you log off Windows. The logon screen is a bitmap image that is displayed by an executable file named logonui.exe. So, the logon program uses a background file in much the same way that you can place a background image on the Windows desktop.
The logonui.exe file is a Windows resource file. Thus, changing the background image file requires that you either hack this resource file (using something like ResHacker, which is discussed in Appendix A, "Using ResHacker") or use add-on software that allows you to select a new logon image and then takes care of modifying the logon resource file for you. Examples of such software are StarSkin and Style XP. Style XP, a software add-on utility, is the safest bet because you aren't trying to modify an important Windows resource file on your own.
You should back up your entire PC before playing around with the logon and boot screens. Because both skin elements involve important Windows resource files, having a backup of your system can help you restore your Windows environment if you run into trouble.
If you install a skinning program such as StarSkin, you can change your logon screen without too much risk. Boot screens are a little trickier, though. Changing the boot screen requires manipulating the ntoskrnl.exe file and another file, the boot.ini file. The OS kernel file is certainly one of the most important Windows resource files. You can try to hack ntoskrnl.exe, but this can result in boot problems. If you really want to change the boot screen, you should use software that can change the boot screen for you. Even products like StarSkin, Style XP, and the Object Desktop Theme Manager (part of the WindowBlinds suite) that allow you to change the boot screen provide warnings related to the changing of the default Windows boot screen.
For example, when you select the Boot Screens option in Style XP, a warning message appears related to the modification of the boot.ini file (see Figure 13.1). The message lets you know that your computer might not boot correctly after modifying the boot screen.
Figure 13.1. Changing the boot screen can be a risky proposition.
Using skinning software such as StarSkin to control your logon screens is just one option for working with logon screens. As I already mentioned, you can also attempt to hack the logonui.exe file. Another software-based solution is the use of a dedicated logon management utility. A number of these are available on the Web, such as Logon Loader (http://logonloader.danielmilner.com/), which enables you to change and manage your logon screens.
You have to decide for yourself whether changing the boot screen is worth the risk. When you consider the amount of time the boot screen is viewable on the computer (typically only several seconds), you might not want to mess with this particular skin element.
Let's take a look at the less risky possibilities for modifying the Windows logon screen. We can then finish the chapter with a discussion of working with boot screens.
Remember that Microsoft does not recommend the modification of any of the core operating system files (and ntoskrnl.exe and boot.ini both certainly qualify as important OS files). However, some software utilities (other than the skinning software previously mentioned) do exist that can be used to change and control the Windows XP boot screen. Examples are Screen Bootyyes, that's its namewhich is available at http://www.startupscreen.net/, and BootXP, available at http://www.bootxp.net/.