Unable to find data

hey all
i've just installed Ubuntu 10.10 on a separate partition on my hard drive , i had windows xp first but now only i can start Ubuntu and unable to start my XP , another thing when i start the Ubuntu i can't find my data i had on my hard disk , i just find empty folders , so i was wondering how can i locate and use my data and how can i start my Xp again ...

...thanx