I vaccinated a couple recently who are going away with Travelsphere...South Africa and Victoria Falls. Latest recommendations are
Diptheria/Polio/Tetanus (one vaccine called Revaxis)
Hepatitis A and Typhoid (one vaccine called Viatim or alternatively Hepatyrix) The typhoid is not really necessary for SA but advisable for Zambia)
Other vaccines such as hep B and rabies are if you are going off the beaten track or, in the case of rabies, more than 24 hours away from medical attention and a reliable source of immunoglobulin.
Yellow fever only necessary if entering from an infected area ie South America or Africa. In the case of going to Zambia it is only deemed necessary if going into remote jungle areas.
Malaria....main risks are in Kruger and Zambia so you should not need to be on tablets for the whole trip, just the latter part. Malarone are perfect for a trip such as this.
The reason I am so interested in this, I am almost ready to book this trip for May 2009.
http://www.fitfortravel.scot.nhs.uk
This website should clarify things for you, it's the public version of the professional website I use at work. This info from me is guidance only, of course it will be necessary to consult your GP or travel nurse.
Janice