That's hard to say, spidergal, because the treatments continue to improve. For many people, HIV is now considered a chronic illness along the lines of diabetes and, with proper treatment, they can live long lives without succumbing to AIDS.
Here's some data on those who go untreated...
Studies of people who don’t receive treatment for HIV show that about half of HIV-infected people progress to AIDS within 10 years of being infected. Three out of four HIV-infected people progress to AIDS within 15 years of infection.
Children who are born with HIV and people who got HIV through a blood transfusion tend to get sick more quickly.
The stages of HIV tend to follow the pattern highlighted below, although actual times vary a great deal from one person to another:
Time After Infection
3 to 6 months HIV spreads within the body and becomes detectable when an HIV test is done.
1 to 10 years A person is HIV, but healthy.
3 to 10 years Minor symptoms may appear.
8 to 12 years Symptoms of HIV or AIDS begin to appear.
Edit: I don't know when those time-tables were created but HIV detectability via HIV testing is down to days, not months.