Hi azaragoza,
Here's an Inline::C solution:

use warnings;

use Inline C => Config =>
    BUILD_NOISY => 1;

use Inline C => <<'EOC';


#define _WIN32_WINNT 0x0500

#include <windows.h>

#define DIV 1024

char *divisor = "K";

#define WIDTH 7

void foo()
{
  MEMORYSTATUSEX statex;
  statex.dwLength = sizeof (statex);
  GlobalMemoryStatusEx (&statex);

  printf ("%ld percent of memory is in use.\n",
          statex.dwMemoryLoad);
  printf ("There are %*I64d total %sbytes of physical memory.\n",
          WIDTH, statex.ullTotalPhys/DIV, divisor);
  printf ("There are %*I64d free %sbytes of physical memory.\n",
          WIDTH, statex.ullAvailPhys/DIV, divisor);
  printf ("There are %*I64d total %sbytes of paging file.\n",
          WIDTH, statex.ullTotalPageFile/DIV, divisor);
  printf ("There are %*I64d free %sbytes of paging file.\n",
          WIDTH, statex.ullAvailPageFile/DIV, divisor);
  printf ("There are %*I64d total %sbytes of virtual memory.\n",
          WIDTH, statex.ullTotalVirtual/DIV, divisor);
  printf ("There are %*I64d free %sbytes of virtual memory.\n",
          WIDTH, statex.ullAvailVirtual/DIV, divisor);

  // Show the amount of extended memory available.

  printf ("There are %*I64x free %sbytes of extended memory.\n",
          WIDTH, statex.ullAvailExtendedVirtual/DIV, divisor);
}

void bar() {
  Inline_Stack_Vars;
  MEMORYSTATUSEX statex;
  char buffer [30];
  statex.dwLength = sizeof (statex);


  GlobalMemoryStatusEx (&statex);

  Inline_Stack_Reset;

  Inline_Stack_Push(sv_2mortal(newSVuv(statex.dwMemoryLoad)));

  _ui64toa(statex.ullTotalPhys/DIV, buffer, 10);
  Inline_Stack_Push(sv_2mortal(newSVpv(buffer, 0)));

  _ui64toa(statex.ullAvailPhys/DIV, buffer, 10);
  Inline_Stack_Push(sv_2mortal(newSVpv(buffer, 0)));

  _ui64toa(statex.ullTotalPageFile/DIV, buffer, 10);
  Inline_Stack_Push(sv_2mortal(newSVpv(buffer, 0)));

  _ui64toa(statex.ullAvailPageFile/DIV, buffer, 10);
  Inline_Stack_Push(sv_2mortal(newSVpv(buffer, 0)));

  _ui64toa(statex.ullTotalVirtual/DIV, buffer, 10);
  Inline_Stack_Push(sv_2mortal(newSVpv(buffer, 0)));

  _ui64toa(statex.ullAvailVirtual/DIV, buffer, 10);
  Inline_Stack_Push(sv_2mortal(newSVpv(buffer, 0)));

  _ui64toa(statex.ullAvailExtendedVirtual/DIV, buffer, 10);
  Inline_Stack_Push(sv_2mortal(newSVpv(buffer, 0)));

  Inline_Stack_Done;
  Inline_Stack_Return(8);
}


EOC

foo();
@info = bar();
print "\n";
print "$_\n" for @info;
[download]

The foo function simply prints the values to stdout.
The bar function returns the same values to an array.

Unfortunately, it works only with Microsoft compilers, but not MinGW. I don't know why GlobalMemoryStatusEx is inaccessible to MinGW - working out why should help fill in my day :-)

Cheers,
Rob