Will a 500 watt power supply be enough?

I have this computer. I want this graphics card. Will this power supply be enough?

The current power supply is 300 watts. The 4870X2 consumes a maximum of 264 watts. The PCP&C power supply maxes out at 550Watts but is sold as 500watt. If I remove the power consumption of my current video card(S) will the 500 watt power supply be enough?

Will barely cut it. You'll be hitting the limit of that PSU. Don't forget, you're also on a Phenom.

Get this instead: http://www.pcpower.com/power-supply/silencer-610-eps12v.html

well, the 9550 is 95 watts, the graphics card is 264 watts, hard drive is only going to be about 9 watts... So 368 watts. What else do i need to be putting in the equation. dvd drive (9?or?less?), cpu fan and system fan, sound card, motherboard? Would it really be "just barely"? I don't plan to add much else.

Is there some way I can find out how much juice the system is currently using? I would really like to be able to just use the 500watt supply I linked. Any higher, and the darn thing is going to have a trillion wires that I'm not going to use. If this supply will cut it, then that's what I'm looking for. The only other thing I would possibly want in this thing is a Phenom 9950. Which would only add 45 watts to that current number.