Photoshop :: How Can I Get Smooth Rounded Edges?

How can I get smooth rounded edges?

Let's say, for argument, I want a "square" with rounded corners. So I take the shape tool at 50px radius and draw my square. Right off the batt, the round parts look like utter junk.

What other technique could yield a better corner?

Also note that I can take the blur tool and blur the corners so they are somewhat nicer, but then if I put a shadow on the box, you can clearly see the shadow doing weird things on the blured part. Obviously, with all the beautiful PS images out there, smooth rounds are easily obtainable, not these wildly pixelated corners the shape tool gives me.

What can I do that can be as easy as the shape tool?