it depends on how many user accounts you have on your xp machine.
if you just have your own account and no one elses, it'll boot straight to that account and right to the desktop.
but if you have multiple accounts, then it'll boot to win xp account selector thing (not sure what it's called). you just click on your name and it'll boot to that account (there's no need to enter a password).
hope that help.
I don't claim to know anything about everything, I just tell people what I know.