With your powersupply you have a couple things to consider. The Watts specified for the products you have listed are the specifications for not at load, meaning when idle or just doing basic desktop stuff. While gaming your components will consume much more power.

The second thing is that the video card you are selecting is requesting a minimum of 300w power supply, granted thats not a necessity. But the big issue which will render it useless is that the video card you have there requires 18amps on the +12v rail. Now let me explain, there are different pwoer "rails" in your PS and each one has its own amperage, this number can vary depending on the power supply, but basically your graphics card requires that many amps on that rail or it will not get enough power. And i cant find a good description for your powersupply but looking at the pictures on Newegg the Amps on the 12v rail looks like a single digit number. I may be wrong. But these are important things to consider, as they can render your hardware useless.

One more thing, the 250W is a rated number, meaning it is not necessarily going to give you an exact 250W. Its just like harddrives, they say 250GB but they give like 246. And that number is also the MAX watts it supports, meaning once you hit 250W at load, the powersupply wont give anymore power and youll get system failure.

Also, does each of your boxes need a combination DVD/CD Burner? Just seems like a waste to me, but thats my opinion. Your going to be using these to box correct and each one is going to have one instance of wow?