>get windows 7 recovery disk
>make bootable USB drive with it on it
>unlock administrator account
>log in
>????
>profit
Get the netbook/pc/whatever
Check whether it can boot from cd / usb
If yes, continue
Install ubuntu/whatever linux on cd/usb drive
Boot your computer from it and choose "try out linux", do not install it
Now use this to copy c/windows/system32/cmd.exe to utilman.exe (make a safe copy of this, you cant get it back if you dont!)
Shut down ubuntu and boot pc normaly
Click the "help thing" in the left corner, a cmd window pops up!
write in these 2 lines
net user administrator /active:yes
net user administrator blahClose cmd window, restart computer
Now log on the admin account with the password "blah"
Do whatever stuff you want
Don't forget to delete the new utilman.exe and get the safe copy back because the cmd window is a huge security risk and yould also get you fired from school for hacking