So my early 2008 iMac needs a new RAM card I think. One 2GB was replaced under warranty but that has since expired. Should I get another of the same and try installing it myself? Both say "ok" in 'about my mac' but the hardware test does not appear if I hold down the D key when I start it up. I've had 12 kernel panics in the last 3 days, so I guess it won't heal itself. Does any one have a suggestion?