I am using Window XP and Mac Ox together but i would like to format window xp . When i tried to format from xp, it said that " windows can't format this drive. Quit any disk utilities or other programs that are using this drives.
This would probably be better asked here,but you can go into bootcamp and erase the partition or
or go into disk utility and erase the partition from there
If you are wanting to format the Windows partition, you will have to do it while in OS X or while installing Windows. In OS X open Disk Utility and select the Windows partition you wish to erase, then go to the erase tab and erase it