there should be a part of your computer on the bottom that screws off with a small imprint that looks like a chip (to squares side by side and teeth on one side) take that off. look to see how the chip is built in. I think the standard way that chips are placed in is that they have the two buttons on the side of the chip. just press those two buttons and it should pop out. then after reading it, unless you read the paper thats probably on top of the chip (don't need to take it out!
!) then it should have the num. or name of the type of chip. remember or write down the type. then go to the store and buy that type. OR go to Pricewatch | Lower prices on computers, laptops, mp3 players, motherboards, computer parts and electronics
and get one for the cheapest you can find (IF you know already what you're looking for!).
I hope this was helpfull!