What Service Pack is installed? I used to know a bug in the scheduler that'd allow you unlimited access too (basically, it'd allow you to be logged in as "SYSTEM")
EDIT:
Apparently it works on SP2 too (at least, here it does, on XP MCE)
I've attached the file.
What it does is add itself to the task-scheduler for the next minute, and then waits for it to be re-launched. This means that you should unpack it somewhere, instead of just running it from the zip
On startup it should say something like "Wait a minute please...", then after roughly a minute a new window will pop up "Google Search: Second World War" with an Internet Explorer icon (It was designed to be used at school, and because of this they couldn't see it in the taskbar
)
Then it has several options:
Run TaskManager -> runs the taskmanager as SYSTEM, from there you can use all those tricks (like the userpasswords trick) to change password (trough File -> New Task (Run...) )
Restart Start-bar -> Kills your taskbar and re-launches it as SYSTEM. Now everything you do from Start will run as SYSTEM.
Kill All -> Don't touch this, this was only to fuck school pcs
Blast me! -> Ditto, unless you want your system to reboot instantly...
Unlock & Start MSN -> Start windows messenger, useful if it's locked at school
Run Registry Editor -> Run regedit as SYSTEM
Kill process -> Kill a certain process
Run Program -> Run something
Explore -> Start explorer
Dos prompt -> Start DOS-prompt.
Don't complain to me if you fucked something up or it doesn't work though
EDIT2:
On some systems task-scheduler is disabled, in that case it will still attempt and ask you to wait a minute, but it won't be launched