Nvidia used the still ongoing Consumer Electronics Show to establish two new high-end products, namely GTX 285 and GTX 295, and thus is back at the top. The fact that AMD will not keep it like this should be obvious, and that is why we have inquired at a, in the past very reliable AMD power, about what things AMD would able to come up against Nvidia with.

Spontaneously two names fell into this conversation: RV740 and RV790. The former is a well-known in the rumor mill, VR-Zone has already unmasked the specifications of the chip, and using the tape-out, you could also conclude that the RV740 would come in spring.
The chip will be the successor to the RV730, although it could still remain at the market some time, and will redefine AMD's middle class. In things of performance the strongest model will move up to HD 4830 and HD 4850.

Large uncertainty on the other hand about an update on the performance segment. Would AMD hold the RV770 current until the RV870 or put an update between, which is quite pushing depending on the launch of the RV870, concerning that Nvidia will send a distinctly modified GT200 in persona of the GT212 into the race in the second quarter.
The rumors included everything from a RV770 with better frequency to a RV770 that had to more SIMD units (960 SPs, 48 TMUs), and also the codenames were shuffled: Super RV770, RV775 and RV790.

According to our source, AMD's next performance chip will be called RV790, enter the market as HD 4900, and be crafted in 40 nm like RV740. There is still silence about the amount of stream processors. But we can assure that there will be more than with the RV770, so that the RV790 will not just be a half-hearted frequency update.
Both chips, RV740 and RV790, are announced for March. Though a launch within the CeBIT would be suggestible, no one wanted to determine the date yet [via hardware infos].