Well, I'm not exactly the person to advice you on this, but did you check on some of the other threads on Arabic? Like
this or
this. If you have Office for Mac that may be a problem (and you have to remove some fonts), and if I'm not mistaken Safari doesn't always display Arabic correctly, so perhaps try Firefox instead. But Zaid did say that the beta of upcoming Safari 3
works better.
But as I said, this is not really my area of expertise, so I hope someone who knows more pitches in
