I don't duggest that , because if you go to kensignton or other ram seller, they usually have a separate section for mac or pc ram. my father tried to use my imac's ram in his PC and it worked.... kind of.... it crashed his computer every other hour, but it worked. so my guess is there are not many different harware differences in pc/mac ram but enough to make the trip unpleasant. so, buy mac ram not pc ram.
unless you are talking about the NAME of the ram, like: PC133 or PC66 etc, in which case, ignore my post.
I have installed 512MB in my Pismo (Kensinton Value Ram) which is now at 640MB and 2x 256 & 1x 512 (again Kensinton Value Ram) which is now at 1GB in my G4 500 Sawtooth. Gave the original "slowwer 3:2:2" Apple Ram to my mothers AMD PC. Had no problems so far running OS 8.6,9.0,9.1,9.2.1(just in Classic, OSX .0.4, OSX .1.
Tried this quite early because the Apple Dealers are taking a fortune (at least 4 times the price of equivalent PC Ram ) around here (in Austria).