I am running 9600gso SLI now.
just upgrade to I5 750 and thinking of getting 5770 CF.
will PHYSX be worth to wait for Nv new card in july?
I would advise you against 5770CF and suggest going with a single 5850 (or 5870 if you want to extend your budget or aren't much of an overclocker). You can see many people in here have already stated "but 5770CF is even faster than a 5870!" and "this benchmark shows yada yada yada" and while this is true, raw FPS isn't everything. You'll have a much better gaming experience on a single card than you will with multi GPU. What do I mean by "better?" Well, it will be smoother (better synced), fewer drops in FPS, and more consistent performance. Multi GPU is great if you need to get performance and there simply isn't any other way to do it (i.e., SLI/CF of flagship cards), but if you can get a single-GPU solution that has performance comparative to a multi-GPU solution, you'll want the single-GPU solution.
That said, you could run a 5850 with one of your 9600GSO's as a PhysX solution. As stated, NVIDIA officially blocked this in their drivers. However, there are work arounds with hacked drivers using Windows 7. It's kind of a pain in the ass, but it's possible and will be the cheapest way for you to check out hardware PhysX with as little risk.
I would also advise against using a single NVIDIA GPU for both rendering graphics and PhysX (i.e., picking up a GTX 470). As much as NVIDIA would like you to believe, their cards can't handle PhysX and rendering at the same time, at least not well, and your performance usually tanks.
As far as whether or not this is all even worth it, your call. I've never found PhysX to be a compelling reason to base a graphics card purchase on. However, you should take a look a few of the games and see if you think it's worth it for yourself (using your 9600GSO's would be a cheap way to do it now before you switch).