Wow, I've just recieved my 4th RMA replacement for a PNY 128mb, 133mhz SO DIMM. This time I ran diagnostics as soon as I had it installed. The "Apple Hardware Test" CD was unable to boot with a memory failure ! There policy is NO REFUNDS, just replacement. I've already have more in postage than the DIMM costed in the first place. PNY recommends PC133 memory, but says on their website that their "PC133 memory is no longer backward compatible with PC100 machines". The failures over the last 12 months caused corruption of data to the point that I had to back-up, format and restore the entire harddrive. Buyer beware Later Parkerdude