When the system needs more ram than it has it will "page" a piece "out" of real memory and stuff it on the harddrive in a place called virtual memory.
The harddrive, being about a billion times slower than real memory, causes your computer to slow down if it needs the stuff in virtual memory. It has to page it back in, which takes time.
big numbers are therefore indicate that more ram would speed you up. small numbers mean more ram wont really help.
Your numbers dont mean anything to me, because I could trigger big numbers by purposely running too many large tasks at once. You should be able to tell whether the system slows down if there's a lot going on, or not, without resorting to that statistic.
