Went to meet the beast head on..
.. and guess what? The Prometric testing center was closed. I showed up 15 minutes early, and there were about 6 people standing outside the test center. The doors to the testing center were locked, and nobody seemed to know why. After waiting about an hour, a security guard came up to us and said the proctor was on vacation. I guess it was too much trouble for Prometric and/or the testing center to notify me, especially when I scheduled it over the phone a month ago. In the end, I spent 1.5 hours driving each way, an hour standing outside, and $40 in gas. Way to go Prometric!