Well, I have to take Steve's "logic" to task. He says:

HIV is not passed on by promiscuity. It is passed on by someone who has it to someone who hasn't.

Trouble is, Steve, the more sex partners you have, the better chance you have of coming across one who has HIV.
If you and your mate have a lifelong relationship and you don't have other sex partners, your chance of getting a sexually transmitted disease is slim to none. Sexual fidelity does help control the spread of disease. So do condoms. To deny the efficacy of either, is equally silly.

-Joe-