C# Definition:

private struct MEMORYSTATUSEX
{
    public int Length;
    public int MemoryLoad;
    public long TotalPhysical;
    public long AvailablePhysical;
    public long TotalPageFile;
    public long AvailablePageFile;
    public long TotalVirtual;
    public long AvailableVirtual;
    public long AvailableExtendedVirtual;
}

VB Definition:

Structure MEMORYSTATUSEX
   Public Length As Integer
   Public MemoryLoad As Integer
   Public TotalPhysical As Long
   Public AvailablePhysical As Long
   Public TotalPageFile As Long
   Public AvailablePageFile As Long
   Public TotalVirtual As Long
   Public AvailableVirtual As Long
   Public AvailableExtendedVirtual As Long
End Structure

User-Defined Field Types:

None.

Notes:

Length must be filled in before calling the GlobalMemoryStatusEx method, using Marshal.Sizeof() method