And as someone e-mailed me, people that have unprotected sex with and HIV positive person don't ALWAYS become infected - so maybe I need to increase the probability of condom protection for that (although I don't know how you'd factor such a possibility).
Bottom line to me is this: if I had a choice between reliving my youth and spending another year in Viet Nam, or having sex with a known HIV infected person for a year (with or without a condom) - I'd take Nam. I had more confidence in the guys I was with keeping me safe than a thin plastic doohickey.
I really don't understand how people feel so indestructible just because they use a condom.