hmm ok, i don't know if I'm still just understanding wrong, or this is a big difference but the one in my computer says it's a 460w and that's 500w. Would that extra 40w be important?

also there is a guy at my job who just got a new graphics card and offered me his old GTX 470 for around $50. Is that worth it? or should I just get a new, better graphics card.