XP is the fastest booting OS Microsoft did. But just compare the same thing.
Under Dos load : a sound driver, a network driver, a video driver, a usb driver , etc..etc...
do the same thing under 98 then under XP. And you will see that XP is terribly Fast!
As i said in a previous post, i boot from Cold to my Front End on XP in 11 seconds. Under Dos, i boot in 15! on the same machine.
Just stop all service you don't need, remove driver you don't need etc..etc..
But for sure, is not really easy to find what you don't need!
Soon, i should do (just have to find time!

) an utility integrated with AtomicFE to maximize XP loading speed in case of a dedicated usage in a cabinet.