how do I "break" an image?

I'm not sure if "breaking" is the right word, but what I want to do is this:

http://www.johnmayer.com/gfx/cover.jpg

At first I thought I could do it by going into Filter -> Stylize -> Tiles and messing with that, but I couldn't get it to work. Can anyone give me step by step directions?

There's probably quite a few ways to do it, but I'll try the easiest one here:

1) make yourself a new square pattern, white lines and a transparent background: see link:

http://www.teamphotoshop.com/forum/vbforum/showthread.php?s=&threadid=4879

2) Fill that pattern over the image (Edit-->Fill-->Pattern)

Edit those little squares to your hearts content