Hi again,
It sounds like you are upgrading an existing configuration, right? I'm confused in that you say it has 64mb of pc100, but it is a PIII running at 133fsb. Whatever the case, make sure you are running at 133fsb, unless you have a 100mhz PIIIE. If this is the case, just add the ram and yuo're all gold.
As Always,
D