Yeah that should handle it fine, but that series of cards is almost dead man, look into an 8800GTX or something. Also, I don't know the upgradablity of Dells, so whatever you buy for it might now work. Also fans are measured in mm not inches.

But back to the original topic, the PSU is known as the only part of a computer that is capable of taking EVERYTHING down with it. That's why when building a custom computer (like mine) a PSU is not the place to skimp on. Mine was 125 dollars and well worth it.