Lock the workstation on a windows machine

hi,

i'm trying to come by some code to help me lock the workstation from the program i'm developing for windows machines (2000 and xp)

i know there is an API, but i think i don't have it, for example i tried this:
#include <windows.h>
#include <stdio.h>
int main()
{
                        if(!LockWorkStation())
                                  printf ("error: could not lock workstation:  %d\n", GetLastError());
                        return 0;
}

according to msdn LockWorkStation() is included on windows.h, but not VC 5, nor GCC (mingw or cygwin) can find it.

another thing i tried is to find something similar to this:

SendMessage(HWND_BROADCAST,WM_SYSCOMMAND,SC_SCREENSAVE,0);

that will lock the workstation by activating the screensaver. everything is fine, only i just want to lock the computer without the screensaver. so maybe there is a parameter other than SC_SCREENSAVE that i can pass onto SendMessage.

the last thing i know of is the rundll trick of locking the Workstation by calling user32.dll or something, but again, there must be a better way

any ideas?

any help will be appreciated.