AMD's new Radeon HD 3800 series graphics cards will be available within two weeks but we still know very little about the performance of this cards, thrustworthy benchmarks haven't been leaked yet.
Though, some industry sources claim that the Radeon HD 3870 will be slower than the new GeForce 8800 GT and will therefore be about $50 cheaper:
Although NVIDIA has launched 8800GT, there are not enough to go around. Maybe we should call it one step ahead of paper launch with small quantities.
With AMD launching it's RV670XT (Radeon HD 3870) at 199, it will pressure NVIDIA to rehash it's pricing. At the mean time, AMD will also launch the Phenom processor and new chipsets at the same time frame.