Duke,
Aren't you the guy who was going to see Dr. Partin toward the end of your last thread? From what you just wrote, it sounds like your internist talked you out of the biopsy. In my case, I had prostatitis AND cancer. And yes, antibiotics reduced my PSA, but never to a decent baseline that I could hold. Much as I wanted to write off my elevated PSA to infection, I couldn't really determine the probablity of cancer until I started consuting with someone who had treated thousands of prostate patients and who was up-to-date on all the recent research and methods. So, my recommendation remains the same: find, and stick with, a good urologist.
Best of luck to you,
7s