"Although DDR is becoming more and more popular (and cheaper as well), PC133 SDRAM is still hanging around. Asus provides the best of both worlds by offering the A7A266 which supports both memory types:
For the do-it-yourself system builder, the choice usually comes down to budget. Only those with the highest disposable incomes will find the Pentium 4 platform attractive. The RDRAM and motherboards available certainly pack a performance punch, but the high cost may be prohibitive to those on a budget. Falling DDR and SDR SDRAM prices and an aggressive pricing strategy from AMD make the Thunderbird and DDR SDRAM combo more attractive to the average consumer.
The ASUS A7A266 ($145 MSRP) motherboard is the only AMD compatible board that offers both SDR and DDR SDRAM support. Capable of supporting Thunderbird and Duron processors with clock speeds ranging from 500MHz to 1.4GHz, the A7A266 works with both 200 or 266MHz processors, making it even more versatile and attractive to budget users."