Recently news about the severe acute respiratory syndrome (SARS) and avian flu viruses has caused significant panic in many countries. These viruses, for Europe still very much a theoretical danger obscure the much more immediate danger of the human immune deficiency virus/acquired immune deficiency syndrome (HIV/AIDS). We develop a deterministic compartmental simulation model to assess the impact of highly active antiretroviral therapy (HAART) and various other interventions (aimed at modifying behavior) in sub-Saharan countries. We calibrate this model using data from Botswana. To our knowledge our model is the first to include all the important factors of the HIV/AIDS transmission. The model shows that HAART alone, at the current implementation level, cannot significantly impact the number of HIV/AIDS infected individuals in the long term. The association of HAART with the treatment of other sexually transmitted diseases (STDs) seems to be more promising and could cut the number of infected individuals by half by 2010.