Paul Ewald in "The Evolution of Infectious Disease" covers HIV. According to the phylogenetic analyses, SIV (the simian version of HIV) is derived from HIV, implying that monkeys got their version from us, not the other way around. I'd be interested in scientific references that show that HIV is derived from SIV. Thanks in advance.
Ewald also points out that it's possible that HIV was a common infection that remained benign in humans for thousands of years and suddenly became virulent due to the adoption of promiscuous habits (e.g. prostitution) in the geographic area of origin of HIV. Ewald uses this to support his theory that virulence is a consequence of transmission rate.
HIV and AIDS are not the same. HIV is a virus, AIDS is the disease caused by the virus. There are many instances of HIV infection with no manifestation of AIDS, and there is at least one case in which an individual (male) was HIV positive and is now HIV free, implying that some immune response got rid of it.
Hope this helps.