It should'nt be a problem at all-my ibook, which needed PC100, ran happily with a stick of PC133.
However, the CAS latency on this RAM is 3, not 2. I would check the owners' manual, or call Sony to check on this, as in this case it's not so much of a performance issue as an issue of having the computer not recognize it. (Macs tend not to be able to use anything other than CL3, which is rare because most chips today run at CL2.5 or CL2).
Good luck!-you're going to need it.