Numerous people, including Russ of compuCheap, have opened up both the turbo-cool 300W from PCPowerCooling and a Fortron Source/Sparkle 300W, and they are exactly the same, in every which way. The Silencer 275 from PcPOwerCooling is a 300W unit but with the silencer fan instead of the standard fan.
This isn't to say they are bad power supplies(in fact, they are excellent p.s's)., but the cost increase is ridiculous. YOu can get a fortron source 300W for under $50, compared to hwatever PCPowerCOoling is charging right now for it.
A 250W of good quality should be adequate, but just to let you know, you can get antec 300W p.s's for about $37.
Mike