Incase anyone cares what real power draw is for a typical system, this chart is getting close to a year old, but it should give you an idea.
PSU companies will always tell you that you need more power, but they aren't being truthful as you can see. Amps on the +12 is probably all you should care about since most PSU's have enough wattage to power almost anything:
Now do you see why I think a vid card that draws 250 Watt is stupid???