Well almost all of the current crop of video cards need a 450 watt power supply or better. I have an ati x1950 prow that's 1.5  years old, and even it needs a 450 or better.

If you end up wanting to add a sli card down the road, yo umight as well double that power supply requirement.

Check newegg and tiger direct for the best power supply prices, but be forewarned that buying the cheapest one you find isn't the best idea... read the reviews, and keep in mind that your system's main cooling comes from it's power supply fan.

Way too many people take way too many things way too seriously.