Which windows version are you using?
Are you actually using xubuntu 10.04 or is that a typo? It hasn't been supported for nearly two years.
Did you create a data partition or install something on that partition?
It would be best if you could post more info. If you have the Xubuntu install medium or any other Linux Live CD, go to the site below and download and run the bootinfoscript. It will output a results.txt file which you can post here. Be sure to read the instructions in the link in the Description box. This will give detailed information on the status of your drive(s).