Well, I don't know if prices are cheaper out in South Africa, but 1, I would wait until the
prices drop in Q2 07
That doesn't show the two processors you are looking at, but the price would have to come down regardless.
If you have the money to blow now, I guess you could go ahead, but the money you save could buy a new motherboard, or more RAM, another video card, etc....the list goes on. You could use the money you save to buy a game or two.
So far as the merits of quad vs dual, yes, there are no games out at the moment that use quad cores. They will in future, but until one comes out, no one will know what the difference is between dual and quad. I've heard Valve is looking to update the Steam engine for multiple cores also. So if you are going to spend that amount of money....
For Vista, well, it is pretty much slower at running everything. And you MUST have at least 2GB of ram if you are going to bother. I would do a dual-boot install personally.
Centurion