Windows 7 Boot Updater is a free portable tool that allows you to change your Windows 7 boot screen animation.
How to use:
Run the tool as admin.
Click Select Animation and browse for the folder that contains your boot animation images. If you do not have any get some from here.
Uncheck Text as it doesn't work at the time of writing this article.
Click Go!. It will take some time and display a message.
Now restart your PC and check if the animation has been changed successfully. If not, then follow these steps to recover your computer.
(Requires .NET Framework 4)