If you must replace your card now, then yes, that 3 cards are probably your best bet. I will ditch the 5870 from the selection though as if you ain't going for multi-display as it may be hard to utilize the extra power from 5870 compare to 5850.
PhysX is not some visual effects on games that you won't see on ATI video card, but a nvidia video card can offload PhysX from CPU to GPU. That means, 470 performs better on games featuring PhysX. Compare to older Nvidia cards, the min fps is increased when the GPU is working hard, which, IMO, is the key to the fermi's series.
The only thing that is proprietary to Nvidia are CUDA and Nvidia 3D vision, not PhysX. That means, you won't miss much with ATI cards in general. However, if DirectX 11 and/or PhysX are your cup of tea, then 470 will be a better decision.
Having said that, if you can wait another 6 months, both companies will probably release a better card as DX11 is a bit too new for this generation as both companies are testing water with the current release. With the extra funding ATI have, their next release will probably be good. On the other hand, Fermi design is promising, but a bit sloppy on the manufacture side. Those little manufacture problems should be fixed resulting a better revision.