There are a few books out there specifically with Raptors in mind.
The first one is THE book on Raptors apparently. I've ordered my copy 2 weeks ago. Will let you know how good it really is
Raptors of the World by James Ferguson-Lees and David Christie. ISBN: 0618127623
Just short of 900 pages it covers all 313 species of the world's raptors. More than 2000 colour illustrations makes it the book of all books. Bit expensive (just under R500) but worth every sent if I listen to other people's comment on this book. (one problem 2,5kg

)
Raptors of the World: A Field Guide by James Ferguson-Lees and David Christie. ISBN: 0691126844 or 0713669578
Condensed version of the above-mentioned book. Got some new species in as well, totalling 338 species. 320 pages, 118 colour plates and half the price of the complete title. But some people have said that in condensing they have taken out some important id'ing points. O ja, it also only weighs a third of the full title's weight.
Sasol Birds of Prey of Africa and its Islands by Alan and Meg Kemp ISBN: Hardcover - 1868727327 Paperback - 1770073698
I've got one of these. Not bad at all. 348 pages. Here you've got a double-page spread for each bird. Lots more info on breeding, habitat and distribution and other things than the normal Sasol field guides. Differences between male, female and juvenile are pointed out. Also similar or confusing species are discussed. Loads more illustrations and photo's per bird as well. Retails: Paperback R170 and Hardcover R300 The one Snoobab mentioned I think.
Sappi Raptor Identification Guide for Southern Africa by Ulrich Oberprieler and Burger Cillie. ISBN: 0958419574
Got one of these as well. Very nice. 286 pages paperback. Again double-page spread on each bird discussed. Excellent colour photographs. Same kind of info as Sasol Birds of Prey. Colour in-flight illustrations on every single one which comes in quite handy when trying to id a bird in flight.
Retails for around R200
They're all available on the normal shopping sites except for the Sappi title but I did find it eventually. Hard one to track down that.
Loads more available but I think that these are probably the better ones for our region.
PS: Just one little thing I forgot to mention. Owls are not featured in the Raptors of the World titles.