please help

I had windows xp on c: and my docs in d:
I intalled vista on c: and now i can not acces my documents on d: becuase I
have them encrypted with my old windows xp.
Now, when i try to load the old windows xp, it hangs up in the boot process.
the xp installation is still in folder windows.old
how can i start xp again to regain access to my documents????
please help