Hello? _All_ Athlons and Durons use DDR on the CPU bus. Most use 100 MHz DDR, while the newly-presented 1.0/133, 1.13 and 1.2/133 use 133 MHz DDR.
The 760 chipset can run either CPU bus speed. What it can't do is decouple the SDRAM bus speed from it - so when you put a 100 MHz DDR bus CPU in it, it'll run the SDRAM at 100 MHz DDR (PC1600) too. Only with a 133 MHz bus CPU will you get 133 MHz DDR (PC2100) on the SDRAM bus.
Other DDR SDRAM chipsets might offer the decoupled bus frequencies.
On the CPU bus side, it's always DDR - the existing chipsets just use normal SDR SDRAM. VIA KT133 is being replaced with KT133A for 133 MHz CPU bus capability.
Regards, Peter