Computer wont load window...bsod

Hello, I have a sony vaio pcg-9s1l laptop that wont start up after the startup info screes runs.
When I turn it on it starts to run the info and then when it is supposed to go into windows it turns itself off. I doubt it is overheating cause I can run it in bios and it stays fine. The computer will not stay on long enough to put a cd in. I detached the dvd rom and still the same and sometimes seems to act up more so when messing with the dvd rom. (the bios lists it still as cd rom) I have xp on it. the memory is 512. I changed the harddrive with my friends and still the same. The big thing is It is not running long enough and doesnt go into windows to try and problem solve anything. I put the bios to default settings but still the same. Anything I can do in bios or is this a lost cause? Thank you for your time.