amd64: why is sizeof(int) =4? why not =8?

[Mitchell Laks <mlaks@verizon.net>]

Hi,

I wanted to find out more about amd64, so I installed the debian distro 
(etch/sid) on my amd64 dual core system. 

I wanted to see if it is really 64 bit. So naively i compiled the following 
example program I found on the internet:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

typedef struct employee_st {
    char name[40];
    int id;
} Employee;

int main()
{
    int myInt;
    Employee john;

    printf("Size of int is %d\n",sizeof(myInt));
        /* The argument of sizeof is an object */
    printf("Size of int is %d\n",sizeof(int));
        /* The argument of sizeof is a data type */

    printf("Size of Employee is %d\n",sizeof(Employee));
        /* The argument of sizeof is a data type */
    printf("Size of john is %d\n",sizeof(john));
        /* The argument of sizeof is an object */

    printf("Size of char is %d\n",sizeof(char));
    printf("Size of short is %d\n",sizeof(short));
    printf("Size of int is %d\n",sizeof(int));
    printf("Size of long is %d\n",sizeof(long));
    printf("Size of float is %d\n",sizeof(float));
    printf("Size of double is %d\n",sizeof(double));

    return 0;

}
and the output is  no different from on my 32 bit system.
ie:

Size of int is 4
Size of int is 4
Size of Employee is 44
Size of john is 44
Size of char is 1
Size of short is 2
Size of int is 4
Size of long is 8
Size of float is 4
Size of double is 8

So how do I see the 64 bittness of the operating system if  not this way with 
gcc? I would think tha size of int would be 8?
uname -a
Linux Rashi 2.6.16.1-meshulum-2006-4-5 #1 SMP Wed Apr 5 13:34:46 EDT 2006 
x86_64 GNU/Linux

Thanks,
Mitchell Lks