PC3200 is compatible with the KT266A chipset, but it will only run at whatever speed the bus is running at. If you run 100MHz FSB, then it will run at 100MHz (PC1600, or 200MHz DDR). If you run at 133MHz, it will run at 133MHz (or PC2100, or 266MHz DDR). To run it at full 200MHz (PC3200, or 400MHz DDR), you need a KT400 chipset or nForce2 or SiS645DX.
Good memory for overclocking would be either Samsung or Corsair. Corsair seems to have the best right now if you spend the cash for their high-end PC3200...