Here's how it works (and where the files are)
Okay, so here's how it works in Windows Vista and Windows 7.
In Windows Vista, there were two animations that people tried to cusomize:
the GUI loading screen (i.e. the little green loading bar)
and
the animated start-up orb (also called the log-on Orb)
In Windows 7, there is only 1 animation:
the animated loading screen featuring the orbs that merge into the Windows flag.
In windows Vista, you could modify the start-up orb by transferring a set of 4 .png images into Authui.dll using Resource Hacker, and thus create your own custom start up orb.
As for the loading screen, this was almost impossible to modify while still maintaining the animation. Only a handful of programs on the net, none of them freeware, could create animated loading screens.
When Windows 7 was being constructed, one major concern was speed in all senses of the word (boot speed, loading speed, shutdown speed, wake-up speed, data transfer speed, etc.). They noticed that many people want a faster boot up from Vista. So, they ran a bunch of schematics and tests, and found that displaying a start-up orb added an additional 6 seconds to the boot time, and the fade-out:fade-in animation from the orb to the loading screen added another 2. This was 8 seconds of unneeded time. So, to greatly reduce boot-time, they cut out the orb, while making the loading screen faster.
To modify the boot resources, you need to look to the following files (in Vista and 7 on a 32-bit system):
imageres.dll (C:\Windows\System32) (change start up sound; change log-on screen background)
authui.dll (C:\Windows\System32) (change the start-up orb; currently being hacked for windows 7 to try and reestablish orb)
winload.exe (C:\Windows\System32) (boot animation [hacked in the past to change Vista boot screen to a static image])
winload.exe.mui (this one in particular; (C:\Windows\System32\en-US) (boot animation [hacked in the past to change Vista boot screen to a static image])
winint.exe
winint.exe.mui (maybe boot screen)
bootres.dll (may have point to other files as it is the Boot Resource Library)
bootstr.dll (is a Boot String Library)
Also, I'm not sure of all the files that are involved in the boot process, but I can tell you how to get a hold of every last one in an isolated location.
Go to command prompt and type bcdboot /? and you'll see what I mean. Bcdboot also reveals a hint to the location of the Windows 7 animation from the following ( bcdboot c:\windows /m {d58d10c6-df53-11dc-878f-00064f4f4e08} [do not type this in, as this is the Globally Unique Identifier which is in common on my system with a lot of the files that have produced custom boot screens in the past; you'll understand when you use the bcdboot command.])
basically, you'll typ bcdboot, the partition and location of the windows core (usually C:\Windows)
then type /l en-US if you live in the United States
then type /s (and then some other partition letter)
and then the entire boot core is copied to that location.
So, with the entire boot core isolated to a particular area, you will greatly increase your chances of locating the boot screen and other customizable features. Have a LinuxLive Cd on hand though, because I don't know if the system will point the boot loader to this device or not.
That's all I can do to help you with your problem. If you want a custom start-orb, you'll have to mess around with it because there isn't a known way to recreate it yet.