<< Actually, I faintly remember benchmarks where 2 sticks were better than one. This was most likely due to interleaving. >>
Not right. From 64Mbit sdram chip, it can do 4-way interleaving already, so a single 128MByte sdram DIMM using 64Mbit chips can do 4-way interleaving. Two of them won't make the memory system faster. Interleaving is done inside the individual chip.