shutdown logos are not animated. startup (boot) ones should be.
(imo it helps you see if the computer is still booting or not)
as for how it's all about palette manipulation and a little hex editing.
http://www.xrx.ca/logoutils/ has what you need
download the Animated Logo Utility if you want to get creative,
that and a good art prog, i find PSP is best for palette work myself.
or just use AddBar if you want to, er, add a bar
you can read a little tutorial here -
http://www.nucleus.com/~kmcmurdo/win95logo.html