2700 Ddr

Hi there...I took a DDR SODIMM PC 2700 out of my PowerBook G4, and want to put it into my friend's iBook G4. I think the spec on her iBook says it takes a 2700, but it might be 2100...won't know until I see the machine. Or even ask her what it is.

Anyway...if it is 2100 in her machine, can I add this 2700? Will it destroy the machine? Thanks!