I take it that you researched this and found out it's not done for this reason?
http://www.jakeludington.com/windows_xp/20060219_change_xp_boot_screen.html does let you change it's content but look at that file you are tinkering with.
The downside is a nonbooting machine.
-> Not worth it.
How can I change the resolution of Windows XP bootup screen? i.e.The screen of Windows XP logo with a blue moving bar
(Change from 640x480 to a higher resolution)
Thanks in advance.