Thinking of upgrading my 17" iMac.I have installed a 512 in the bottom but have a 256 in the top. I think the limit is 1 gig total 512MBx2. Or is like the ibooks that took 1 gig chips in their user slot. I would also like to upgrade the hard drive and optical drive, any ideas? I was thinking 250 GB and a DL DVD burner. I was planning on taking it to a local Apple specialist for the upgrades. I don't feel like cracking that eggshell myself. Thanx I.