Are my potatoes OK?

I know I've left that July 4th post lingering, but I wanted to get this one up. I'll elaborate on the other one soon.

The past couple of days, coinciding with the summer weather that has finally arrived, I've noticed that our potato plants don't seem to be doing so great. Many of them are turning yellow and getting all droopy - quite clearly, they're dying. Now, I know that eventually the plants die back, but I don't think that is supposed to happen for quite some time. But this is our first attempt at potatoes, so I really don't know. Here's what some of the plants are looking like (click on the image for a bigger view):


I'm starting to get nervous about our potato crop (or potential lack thereof). So, while in the garden this afternoon tying up some of the tomatoes, I decided to do a little digging around the potatoes to see what was going on. At first I couldn't find anything that remotely resembled a potato (unless you count rocks). Now I was very worried. I decided to try another spot and after a few seconds my fingers brushed up against something that seemed promising. I carefully brushed more dirt away and to my great surprise, pulled up this guy:


Looks like the potatoes have done just fine. :)