I read about upgrading my IMac memory and ordered the 4G of memory from Crucial since my <2yr old computer memory is no longer stocked at the Apple store.
It was all done in less than ten minutes, until I turned it back on and got a sound I shouldn't be hearing. Kind of like a sick foghorn. So, I uninstalled all the new, installed one of each etc etc. Same sick sound. RE-installed the old 1G. Same sound. Fortunately, the resident IT man was on his way past and so he and I went through the same processes.
Finally he shoved those little memoryboards in even harder and there was a subtle but distinct click. I had already dented my fingers trying! Amazing. But the proof is in that little info screen. I'm lovin' the increased speed.