How To Create a Custom Boot Logo for Windows Vista.
First download and install the freeware Vista Boot Logo Generator. This is helpful for creating the correct logo image type. Just make sure that you 'Run As Administrator.
Now select a bitmap image, and save it on your desktop. Choose two 24 bit .bmp versions of this image. One needs to be 800×600, and the other has to be 1024×768.
Now take ownership of the file as follows. Open an administrator command prompt. To do so, type cmd in the start menu search box, AND HIT Ctrl+Shift+Enter.