Macbook Random Shutdown

I bought my macbook in june with 2.0 ghz 1gb ram and 80gb hard drive. In November of ‘06 is when it all started. I was typing a research paper and was on page 8 and hadn’t saved since 4 when my laptop randomly shutdown. I was quite angry because I lost a lot of writing but I thought nothing of the crash and booted up and began working again. BIGGEST MISTAKE. All of Decemeber, February, NO crashes at all and no problems. Then it all started back up in March while I was surfing the web it shutdown. I booted her back up and decided I would call applecare if happened again. Sure enough two hours later it did. Unfortunately it was past six so I couldn’t get anyone live from applecare. The next day I had no problems but the day after I had another crash. A week then went by no problems but then the crash happened that put me over the edge. I called applecare and they asked me to check if I had upraded the firmware which I had. They then went through with me a series of tests. From doing the soft reset or whatever it is when you hold all those keys at startup. We then headed to using the install disks and going to check if there were problems. Then he had me reset or check my ram for problems. He told me that if it happned again after this to take it in to the applestore or mail it to them. Luckily I live in Chicago so getting to the store is not a problem like some of you unluckier people. In the end we didn’t find any problems for sure. When I booted my computer back up after getting off the phone everything was good. Two and a half weeks went by with no crash until TONIGHT. It happened again. I was really hoping it was fixed. Im heading off to the applestore tommorow. After that Ill inform all you what happens there. Anyone got anything I should do there or ask?