I wouldn't dismiss the 4x00 series.
It's the first chip in AMD/ATi's new strategy of making powerful and very cost effective GPU's targeted at the mainstream. For the high end they're now going to jam together multiple chips onto a single PCB. AMD/ATi have streamlined their chip production methods and can create more chips, while doing it for less cost, than Nvidia.
The 4850 is rumored to be at least 10% faster than the 9800 GTX at a 200$ launch price. The 4870 is supposed to be 40% faster than the 9800 GTX and will launch for around $300. The 4850 will be out this month and the 4870 will be out in July. The 4870x2 will be out in August at $500 to combat the Nvidia 280.
The new Nvidia chips, on the other hand, cost 100$ per die to make. On top of that Nvidia is getting around 40% yields when they make a batch. This is increasing the launch prices for the GeForce 260 and GeForce 280 to 449$ and 649$ respectively. Granted they are faster chips but they cost a lot more. They also use a lot more power and thus will require a larger power supply than the Radeon 4x00 cards.
So bottom line, Nvidia is sticking with the strategy of making a huge beast of a monolithic GPU. Nvidia then cripples it to market it as a mainstream card, where most GPU's are sold. Their GPU's will be faster but will also be a lot more expensive.
AMD/ATi is taking a new approach of designing chips from the ground up to be targeted at the main stream market. Which is, once again, where the vast majority of GPU's are sold. Chip for chip AMD/ATi's product will not be as fast but, but they will have a very very good price/performance ratio. AMD/ATi are basically hoping they can hit a price performance ratio that Nvidia just cannot match with its more expensive to produce GPUs.
Anywho, we'll see how it goes in the next couple months.
