u don't die of AIDS. You die of an AIDS related illness. AIDS is a virus that breaks down your immune system and leaves you susceptible to catching minor illnesses which ultimately kill you. What the drugs do is prevent full blown AIDS developing. The person is still HIV+, the present virus which develops into AIDS, and can live thereafter a normal live so long as the AIDS trigger is kept in check.
I wouldn't worry about the virus mutating externally. It doesn't last long outside the body anyway. The reason it is so virrulent inside the body, and successful, is that it mutates when attacked by the drugs leaving it almost indestructible. It's quite a f*cking thing that the human race can be defeated by something so ancient and microscopic yet so intelligent. Scary when you think about it...
