Installing anything in an iMac can be tricky, because you have to open the housing. It's more like working on a TV set than a computer, really.
Upgrading the memory requires removing three screws on the bottom of the housing, then popping off the bottom. You have to pull pretty hard to get it to open up. Once you have it open, you disconnect several cables and remove three more screws. The logic board and drives are all on one unit that slides out. Then you have a metal cover to pop off to get to the memory sockets.
The toughest part is sliding the logic board/drive unit back into place - if you don't have it lined up properly, your CD drive won't open. It's quite common to have to open the machine again and reseat this unit several times before it works properly, at least if you've never done it before.
Would you feel comfortable replacing a tube in your TV set? If so, the iMac won't be a big deal for you. But if - like most people - you are a bit technophobic, call a pro for this one - you'll be glad you did, or at least not sorry you didn't.
The newer iMacs are much easier, but you've got the original model that was a real pain. Save yourself some headaches and get help unless you're pretty technically adept.
DH
