YOU GUYS ARE ALL WRONG. well not literally. but i just wanted to say that.
no but all kidding aside, the dell ps is not 250. They rate their powersupplies conservatively and in actuality ur ps is closer to 350 than it is to 250.
I'm not sure whether it's enough power because u have all those other components, especially ur 3.0 cpu.
But don't think of the ps as 250, think of it as 350.