I bought a G4 400 Tibook, and it has 2 128MB chips in it. One says 133 on it and the other says PC100. Is that bad?? I don't want to fry the computer... I would like to jump up to 512 133mhz RAM and keep the 128 133mhz chip, so I have more breathing room Know of a cheap place to buy some RAM???? Thanks!