I spot that the R380 is a reduced version of R42X, whilst R370 is very similar to Radeon 9600 XT.
The most thrilling card is naturally R423 and R420. As early as when Radeon 9700 Pro was released, the ATi CEO emphasized that R400 (as it was called back then) would be the actual step forward. Considering the fact that the world thought of Radeon 9700 Pro as a gargantuan step ahead, it'll be terribly interesting to see what R42X has to offer. As the name implies, this is a product even more smashing than the one ATi referred to by the launch of Radeon 9700 Pro.
Beyond that, it has been rumored that PCI Express will be a much greater step ahead from AGP 8x than what AGP 8x was from AGP 4x.
According to them previews of these cards will be available in February 2004.
Source : Nordic Hardware