The movie

There is also a film made in 2003 of "Holes".

In the film Khleo Thomas play the role of Zero (on the right side)
[This really does not fit the type I imagined while reading! I expect that Zero seems more, well, stupid than 'sweet'.]

And also Shia LaBeouf as the lead role of Stanley Yelnats (on the left)

There you can get more information about the film:
http://www.imdb.com/title/tt0311289/
http://en.wikipedia.org/wiki/Holes_(film)