Basically open the ZIP file and extract contents, add reg file to Registry and then reboot, it works for sure on BOOT SPEED but for application loading i can't really tell as things come up straight away to start with...
YOU NEED: XP Pro SP2 or HIGHER
NOT: Below XP SP2...or Server Shadowfox unless ya wanna risk it
This tweak is supposed to add the future Vista speed to XP, it makes parts faster anyway