The amps available at 12v is more important than the wattage.
Since the card you listed does not need a auxiliary 6 pin pcie power lead from the psu, it will be entirely powered by the pcie slot.
Most likely, your psu will be adequate if it is of reasonable quality.
Thats good to hear, thank you, but just to be clear, I do plan on upgrading the PSU but I need the GPU now. I don't plan on doing anything extensive with my PC now, or at least more than my current 528MB GPU could handle. I should be okay, right?
Running a PSU beyond it's rated amperage increases chance of failure and decreases longevity substantially. I do not recommend doing it. If that PSU fails, it might take the graphics card (among other hardware) with it.