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.