Do I need a HK visa in transit for 5 hours at Hong Kong international airport?

While coming from United States to Nepal In May 2011, I came through Hongkong. I did not need a Hongkong visa then while I was in transit as I was informed that I need Hongkong visa only if I spend more than a day at the airport. I am going back to the States in Aug and I will be in transit in Hongkong for 5 hours. Do I need to get a HK visa?