Just tossin' this out there -
The commonly accepted theory (or possibly still just a hypothesis at this point) is that the HIV first spread to humans from some sort of monkey or ape. For the most part, HIV is a sexually transmitted disease. If you have sexual intercourse with someone that has HIV/AIDS, there is a good chance you will acquire it as well. That person who had it first got it from someone else (likely through sexual contact), and so on down to first cause - someone had sex with a monkey?
Okay, even saying that's possible, or the likely source of the AIDS virus, it doesn't stop there. Where did that monkey/ape get HIV from? Sex with other monkeys/apes? Eventually, if you go back far enough, there has to be the first victim of the virus. Given the radical mutating ability of HIV, it's possible that it first started out as some other sort of virus that affects primates, and over time evolved into something that spreads easily through sexual contact (a useful biological mechanism), and continues to mutate to make it hard to develop immunity or find a vaccine (another useful biological mechanism).
Also, I don't think it's impossible that it was first created by humans as a bio-warfare agent (I just think it's highly unlikely). The fact that the virus is so tough and has a dastardly set of qualities (mutates constantly to resist immunity/vaccine, affects the immune system of its victims directly - weakening it, and spreads through sexual contact), makes it almost too good (from the virus's perspective) to be true. However, I have full faith in evolution's ability to create all sorts of nasty, destructive organisms - humans of course being one of them.
BTW, I once did volunteer work for the Red Cross as a HIV/AIDS peer educator at middle schools and high schools. I'm proud of my opportunity to help educate people on the dangers of the disease, how it is acquired, and how to prevent exposure to it.
It is my view that if it turns out that this disease cannot be defeated by our immune systems or our medicines, the only other option is to win by attrition, isolate the disease to a point where it has no where to spread - this means taking whatever precaution necessary to avoid exposure to viruses sexually, or otherwise. Eventually, and unfortunately, the victims of the disease will all have died, and the virus will die with them.