Can you offer some help with buying a power supply?

My computer is only a about a year old or so. I’ve decided with my income tax I want to put in a nice graphics card, since I have pretty good RAM and CPU right now.

Problem is my current power supply is only 300w, the graphic cards I want need 350–400w.

I’ve been looking at newegg.com. I also went to best buy but everything seemed slightly overpriced to me anyways.

This is the power supply I believe I will end up buying.

http://www.newegg.com/Product/Product.aspx?Item=N82E16817182074&cm_re=power_supply_400w-17–182-074-Product

And compared to Best buys stuff, I’ll save about 20–25 dollars.

Any other advice or power supplies you can tell me about before I make a final purchase?