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")
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
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