I am looking at a new video card. Will I need a new power supply?

I have a 430 watt and the card says minimum 630 watt. I used a chart to estimate what i am using now and its only 300 watt. Will i be ok to run the card or will i need a new power supply? I am thinking they over rate the watts to be safe.|||Yeah as long as the video card uses less than 130 watts. You don't mention the video card. That might help.