Here is thr page that comes up when you Google AIDS plus South Africa:
Wikipedia (just google it) will also likely be a good source.
These are likely to lead you to lots of good places to support your argument.
Off the top of my head, I would say that AIDS IS a huge problem in South Africa - as it is in sub-saharan Africa generally.
I do not know if it is the biggest problem - I would not be surprised if it is.
Nelson Mandela has bravely used the recent death of his son from the disease to attempt to combat the stigma and ignorance about the illness that is rife in Africa and which hampers efforts to prevent and treat it. You may recall that a South African leader tried to say, for instance, that HIV does not cause AIDS.
Some African leaders find it distressing that the disease appears to have originated in Africa - considering this fact somehow shameful - or perhaps fearing that it will be used in a racist manner - and so have delayed the recognition of the enormity of the problem.
I suspect SA, which prolly still has a better health system than most African countries, is likely to be better placed to manage things, though.
I would guess that, as in other African countries, the disease is leaving many orphans, to be cared for by grandparents.
The cost of the drugs will also be a major problem.
That is all I can contribute!