You need a motherboard using the AMD 760, ALi MAGiK 1, or Via KT266 (yeah, right) chipet to use DDR memory (with an Athlon anyway).
The Abit KT7A CAN use a 266mhz bus. To do so, you either have to have a 266mhz FSB Athlon, or you can overclock a 200mhz FSB Athlon up to 266. You of course have to have a multiplier unlock athlon.
133*9 = 1.2ghz
it should be really easy to try out using your motherboard.