Want to change your boot screen without patching your actual OS kernel?
Stardock has a free program in development to do just that and the first alpha is now available:
http://scripting.stardock.com/private/bs_current.exe
BootSkin replaces the boot screen by creating a device driver that does the job. This has several advantages:
1) It will work on Windows 2000, it'll work on Windows XP, and it'll work on Longhorn 4051 it seems to work. Heck, it probably works on NT 4.
2) This has been implemented in the way that Microsoft would probably do it (or arguably how they should have done it). No patching, no hacking, totally safe.
3) No need to "back up" your kernel. If you somehow blow up your system, you can just boot up in safe mode and uninstall it.
Limitations:
Right now it's no better no worse than the regular boot screen. That means 16 color VGA (640x480).
What's next:
High resolution, true color and animation. But these won't be for a bit. We want to make sure this works well on everyone's system. Creating your own boot screens is incredibly easy. Just look at the included ones in the directory it's installed to (\program files\stardock\wincustomize\bootskin) and go from there. You don't even have to do progress bars if you don't want to. We'll have a bunch of examples as soon as we put some other projects together but hopefully you'll be able to figure out how to do these on your own. Remember though - 16 color (that's 4 bit) only right now since it's VGA. Same as regularly boot screens.
But this is just to get things started and make sure there aren't any problems. It's been tested extensively internally but usual caveat: This is an alpha, use at your own risk, assume it will blow up your computer, kill your pets, set the house on fire, etc. No problems reported so far.