These are some really interesting numbers here. Move away from Vantage due to it being a synthetic benchmark and move away because it doesn't make the greatest use of PhysX; look at the numbers we're getting from Batman AA and Dark Void, two games that really make use of PhysX and the numbers are very interesting.
Under both these games we can see that when PhysX is turned on the GTX 470 offers better performance across all resolutions in both the minimum and average department. Now, before you go thinking that it's better because it's two cards and costs you more, you have to remember that the whole point to this article was looking at two $500 setups; the cost of a GTX 470 and second hand GTX 260 is identical or slightly cheaper than the cost of a single GTX 480.
Sure, in the perfect world you could get the GTX 480 and add the GTX 260, but it again moves away from the point we were trying to make about the best setup for a game with a $500 budget. At the same time we could've added in a ATI option with a PhysX card, but let's be honest, the lack of official support means that it's not a worthwhile option.
Something else worth taking out of this article is with the depreciation costs of the GTX 200 cards or just video cards in general; instead of selling it off when you decide to upgrade to a GTX 400 series, keep it and use it as a PhysX card.
If PhysX is a high priority for you, I would probably suggest the GTX 470 and a dedicated PhysX card any day of the week. The best thing as well; with the overclocking ability on offer from the GTX 470 you're going to be able to get GTX 480 or better performance which means that for $500 you could get a setup that will perform significantly better. While for the same money you could get a single GTX 480 and overclock that, you won't have a dedicated PhysX card.
It's worth remembering that if you're a PhysX fan, buying a GTX 480 isn't necessarily the best option, especially when it comes to higher resolution gaming. I think with games like Mafia II coming out that are going to make great use of the technology, a dedicated card is going to become a popular option.
With the GTX 460 also around the corner, you could well end up with a GTX 400 series card as your PhysX card for a good price in the near future. PhysX is a great technology, but it's worth remembering that for the price of a GTX 480 you can get a GTX 470 and GTX 260 for the same money which will perform better.
Out of all this, though, you have to remember, when you play a game that doesn't make use of PhysX, the GTX 470 is always going to perform behind the GTX 480 setup. But hey, that's why we have overclocking.