I have a 1.25GHz eMac with a 512MB & a 256MB RAM chip. I've read that it max's out at 1GB, which means that I can only replace the 256MB chip with a 512MB chip. I've found compatible 1GB chips. How much RAM can I put into the 2 slots to get the most out of it? I'm looking to use it with FCP 6 & DVD SP 4.