How To Create a Custom Boot Logo for Vista
 

First, download and install the freeware Vista Boot Logo Generator. This helps creating the correct logo image type.
Then select a bitmap image, and then 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. You should open an administrator command prompt. To do this, type cmd in the start menu search box, AND HIT Ctrl+Shift+Enter.

Now Run this command:
takeown /f C:\Windows\System32\en-US\winload.exe.mui

Then Run the following command:
cacls C:\Windows\System32\en-US\winload.exe.mui /G uresname:F

After doing this, copy (overwrite) the created file, in your C:\Windows\System32\en-US\.

Lastly, type msconfig in the start search bar and hit enter.

Under the Boot Tab, check the “No GUI boot” option and click Apply/OK. Reboot.

It is advisable to always create a System Restore point, first!