if u have 320mb of pc133 sd ram in ur machine and u ADD a stick of 64 pc100 MORE

will that be ok? or is that a problem

Aloha
what kind of chip ya running and what is the bus speed ?
you will drop yor bus down to 100
ya can do it but would recomend against it
an extra 64 is not worth it with the price of memory nowadays
at least my thought

if u have 320mb of pc133 sd ram in ur machine and u ADD a stick of 64 pc100 MORE
It really depends on many things that I can never seem to pinpoint. On some occasions it's gone off without a hitch for me, but several times it has caused numerous problems, from machines restarting themselves constantly to not booting at all.
My recommendation is, with memory so cheap right now, is just to buy a couple of identical 256's. You'll get more bang, and chances are you won't have a problem.

Again, keep in mind this suggestion is just from my past experiences and heartache with RAM.