You do need to download the Windows Vista boot logo generator which can be freely obtained at Dan's Blog.
Next you will need to have an image in the formats 800x600 and 1024x768 saved as 24-bit BMPs. For this you can use any image viewer or image manipulation software(Photoshop/Gimp for instance).
Once you have the two images.Start the Vista boot logo generator and select the two images from your computer.
After Selecting the Files, Save Boot Screen File As from the menu and move the generated files into the folder System32\en-US of your Windows Vista installation.
You’ll also need to make sure the /NOGUIBOOT option is enabled in the MSCONFIG tool, otherwise you’ll only get the old 16 colour boot screen.