I'm not exactly sure what you're referring to here... Are you talking about the Windows logo boot screen with the moving bar? Or are you talking about the Computer BIOS boot screen that you would typically see 1sec or so from pressing the on button(typically a manufacturer logo)?
Wincustomize's tutorial there is specifically referring to the Windows boot screen (specifically with use of their BootSkin app), NOT the bios one. The WINDOWS boot screen (If I'm not mistaken) has a pallete limitation of 256 colors, while your bios boot screen will usually have a pallete limitation of 16 colors or less. It's probably possible that maybe certain motherboards would allow their bios logos to be more, considering I'm speaking from years of "older" comp experience, but I doubt it, since manufacturers wouldn't really want to pay the extra money for more space on a mobo's limited cache JUST for a high quality bitmap image.
Beyond just a pallete limitation, altering your bios boot screen is a dangerous process if your mobo manufacturer didn't already open the door for you with some sort of software...
I have an HP Vectra VL400 and I plan on trying to alter the Bios image as well, but I'm going to have to try and find some sort of resource on how to hack a bios flash update with my own image to do so... very risky...
Then again, if you were just referring to the Windows boot screen.....256...
