I've seen the first two in theaters, and Monster House is out on DVD I'm pretty sure, so it shouldn't be hard to catch. Of the two I've seen, I am not sure which one gets my vote. Cars is extremely well done and very clever, but Happy Feet really blew me away with the originality of the story and its commitment to its weird blend of nature facts and music. The sequence with Mumbles in the zoo struck me as pretty dark for a kid's movie, and I'm glad they put it in. So right now, I'm leaning towards Happy Feet...
And for something completely different, click here to see a neat poster by Don Rosa that illustrates the evolution of Uncle Scrooge.