Access a user acount of one os from another

Hello,

I have two operating systems in my computer( Both Windows XP ) . There is some problem with one of the os system. Whenever i select that os system an error occurs and my computer is restarted. The User account in that os is password protected. I am able to access all other data in my computer but the one that are in my document section of the password protected section is not accessible. How do I access those datas???