hehe, i know about this sort of stuff coz i actually used to make simms and dimms
you can put 66mhz and 100 mhz ram into your machine.
it will work...BUT....
if your bus runs at 66mhz, thats fine, coz it means your 100mhz ram will only run that fast anyway. will make no difference
however if you put 66mhz ram into a machine with a bus speed of 100mhz (most new machines) then it will only slow down your machine coz the ram will take longer to do whatever ram does.
so if you have 128mg of 100mhz ram, and want to add 32 mg of 66mhz ram, you may as well leave it at 128mg.
afaik ecc is hardware. just makes if faster and a lot more stable. like connecting a modem and isdn at 44000kbs. the isdn will be smother connection. get the idea?
and fo rthaose that really have no clue, simms must be inserted in pairs and max at 32 mg and have 72 pins
dims can be inserted seperately and come in 128mg chunks and have erm.. forgoten! anout 164 pins or something!
and to end, if anyone want s o buy any 16 mg 66mhz sdram, i have about 5 for sale. going VERY cheap. oh, and i built them myself, but dont worry, they work perfectly coz i had them in both my last pc and my mothers present pc.
have a nice day, and if im wrong about any of this crap, feel free to berate me