I've not had any slow booting times.
My XP machine is a P3 1gz.
This is to anyone that has installed XP and cannot boot at all!!
You may have needed to have cleaned out any spyware before you installed the service pack update.
You may not get this exact error message as shown in the site below, but because SP2 guards against spyware you need to remove certain spyware before you install SP2, so you need to uninstall SP2 and do that. heres how:
http://support.microsoft.com/default...t=windowsxpsp2
This may also be of use:
http://support.microsoft.com/default...t=windowsxpsp2
Maybe for the Slow Booting people, you may need to run a complete virus scan, or try this website:
http://support.microsoft.com/default...t=windowsxpsp2