From the NOLS Wilderness Medicine book (page 250, 2008 edition):

"Incorrect information persists on how long to boil water before it is disinfected. The common diarrhea-causing microorganisms are sensitive to heat and are killed immediately by boiling water. The protozoa Giardia and Amoeba die after 2 to 3 minutes at 140 F (60 C). Viruses, diarrhea-producing bacteria, and Cryptosporidium cysts die within minutes at 150 F (65 C). By the time water boils, it is safe to drink."

Good luck!