When it's at the post screen (before it tries to load Windows), press the F8 key every second or so to try to prompt the safe-mode extended menu. You'll know you're at the right menu if you see the option "Disable Automatic Restart on System Failure." Click on that selection, boot into Windows, and then write down and post the information that the blue screen is giving you. Such as the error code (Generally 0x00000somethingsomething) and the error description, such as "SYSTEM_SERVICE_EXCEPTION." Then, we can begin to help you.