If possible at all, add R 400 more, and get the official GT5 wheel (DFGT), if you read reviews you will notice people had some problems with the Force Ex while playing GT5 prologue, and the wheel is smaller size than other wheels. I would suggest the Logitech Driving Force GT (DFGT), which costs about R 1400. I got it for preparation for GT5 too :P, bought with GT5 prologue for R 1499, its a very nice wheel!
GT5 looks beyond epic!
Edit : Question; why is this in PC Hardware section lol :P