The 5770 doesn't perform that much better than a 260. The fermis are way more expensive than a 5770 as well.
There might be low end fermi cards released but not anytime soon. You should be asking yourself if you should get a 5870 or a fermi since those two cards are similarly priced and provide reasonable gains from the 260.
He is probably after directx11 capabilities. As everyone else here stated, wait and read the reviews and see how it ends up price wise. You may see a little shifting in the price of the current cards already offered...
my motherboard can do both i just want a performance increase from my gtx 260 i know the fermis will cost more but if they are a huge difference from a 5870 or a 5850 or even 2x5770 then ill wait thank you everyone who as answerd
If you want better performance without spending a lot, that usually means AMD. Nvidia simply prices their cards to high. They do have PhysX, but not many games use it. Batman AA is the best game out that uses it. I've seen the demos of PhysX and while its nice, its not something I HAVE to have. Bigger explosions, more paper in the wind, clothes moving, etc. Pretty, but nothing amazing.
GPU accelerated Physx is rare and mostly insignificant. Its been around a long while and only 2-3 games are really noticeably superior with it enabled.
If you want better performance without spending a lot there are two options I would recommend. Another GTX 260 for SLI or an HD5850. I'd go with the HD5850 if you can afford it. At stock it is a bit better than the GTX 285 but it overclocks crazy amounts. The card allows for the core voltage to be raised which has enabled people to usually get speeds between 1000-1100mhz. That's a 40-50% OC which is incredible and easily better than 2 GTX 260s. It will also be DX11 compatible, use much less power, give off much less heat, have no SLI scaling/compatibility issues, leave a slot free for a future upgrade, support 3 monitors, ect.