pthread issue

Hi,
I have a pthread issue here.
I am trying to compile a small pthread code

 #define errexit(code,str) \
 fprintf(stderr,"%s: %s\n",(str),strerror(code)); \
  exit(1);

 /******** this is the thread code */
 void *myfun(void * arg)
 {

// something something

}

 /******** this is the main thread's code */
 int main(int argc,char *argv[])
 {
   int worker;
   pthread_t threads[NTHREADS]; // holds thread info
   int ids[NTHREADS]; // holds thread args
   int errcode; //* holds pthread error
code
   int *status; //* holds return code

   // create the threads
  for (worker=0; worker<NTHREADS; worker++) {
     ids[worker]=worker;
     if (errcode=pthread_create(&threads[worker],// thread
struct
                    NULL, //* default thread
attributes
                    myfun, //* start
routine
                    &ids[worker])) { //* arg to
routine
       errexit(errcode,"pthread_create");
     }

   }

/*

some other code

*/

   return(0);
 }

I tried compiling this on a Windows commandline with g++ compiler

C:\C++Files>g++ -lpthread Thread.cpp
E:\DOCUME~1\VISHAL\LOCALS~1\Temp/ccaZD7xf.o:Thread.cpp:(.text+0xb4):
undefined reference to `_imp__pthread_create'
collect2: ld returned 1 exit status

I am not sure why I am getting this error.

any suggestions and advice ?
Guddu