Definately. The tech guy is too used to specs. A PC-133 Module will undoubtedly work, however, you will be underclocking the RAM to 66mhz instead unless you overclock it to 133mhz FSB(which is very unlikely with the Celeron). The optimal FSB for PPGAs is around 100mhz, and 112 for FC-PGAs(Celeron 2).