Possible Duplicate:
What is private bytes, virtual bytes, working set?
I'm reading a project and programmer write this code to check program memory
if ((Process.GetCurrentProcess().WorkingSet64 + Process.GetCurrentProcess().PagedMemorySize64) > (long)2048* (long)1024 * (long)1024)
{
    Program.Log("memory is over 2G! ----- !closed!" );
    Restart();
}
I want to know why there are PagedMemorySize64 and WorkingSet64 for calculating the current memory size.
Is WorkingSet64 not enough?
Is it true?