You can kill a process with "taskkill /IM notepad.exe" under Windows XP and above.
However, under Windows 2000, this command is not supported. If you copy this taskkill.exe from XP to 2000, you will get a not supported warning.
So, you need other executables to do this.
Microsoft provides us PsKill to do this(even kill process in a remote computer).
Download PsKill.exe from http://technet.microsoft.com/en-us/sysinternals/bb896683.aspx
Just substract it and copy it to system32 folder.
Run like this pskill notepad.exe.
Remember, the first time you run this command, you need to agree a license.
or you can try this one http://www.beyondlogic.org/solutions/processutil/processutil.htm