Hi, Sorry in advance for the really long post. My ibook was running really slow, so i decided to get some more memory. i'm no computer expert but i used to work in the IT dept and have replaced memory before (in pc's). Anyway, i went to my local computer store, told the guy there what kind of computer i had. (ibook G4, 14-inch with a built-in memory and an empty slot). He looked it up on the system, figured out what i needed and i bought it. It was a Corsair 1GB DDR2 667mhz. He said it was exactly what i needed. I didn't question him. Tonight, i go to install it, and it doesn't go in easily. I got it in though, and turned on my computer, and it wouldn't start. i took it out, and it started fine. I went to some online forums about installing memory on my specific model and people were saying you really need to force it in there, more than you think would even be safe, but it takes a lot of force to get it in, so i thought maybe it didn't work the first time because it wasn't in all the way. i kept trying, and i got it in further, thinking i did it. i went to turn on the computer, dead. So, i took out the memory, and now my computer still won't start. NOTHING. I went back to the store, told them what happened, and i spoke to a different salesman than yesterday, and when this guy looked at what i bought, he said it was definitely not the correct one. He said DDR2 is definitely not compatible with the older iBook. He also said that he looked on his system to find out what type i really need, but the system wouldn't show my model (because its a few years old). Pretty much, he said that the other employee messed up because the computer wouldn't even show him what i would need. But what i would like to know is what's wrong with my computer exactly? did the mother board fry? did i lose everything? do i need to send it into mac for repair? how screwed am i? and also, is the store responsible for this at all? The sad part to this story is that in early august of this year, this laptop's battery stopped working, and it was a problem with the power supply. I sent it off to mac and they fixed it, but when it was returned, it wasn't turning on. i sent it back again and they said the motherboard had to be replaced. luckily that happened a month before my extended warranty expired, but this time, i don't have a warranty anymore. Any insight on my problem? Please someone, cheer me up. Tell me there is something i can do to save my computer and that my motherboard isnt fried again. Can putting the wrong memory in your computer completely ruin it?