U can use security in Windows XP if ur file system is NTFS. Using the security settings u can make a partition available to only selected users. To use this feature u need to have NTFS file system and u need to disable sime sharing in Windows XP. This u can do by going to Explorer window and click Tools -> Folder Options -> goto view tab and deselect the Check box named "Use Simple Sharing".
Now go to My Computer, select the drive name, right click and goto properties, Goto security tab, Here add users/groups u would like to allow access to and remove the others. Make sure u remove the group Everyone from the list. Here u can also set the access permissions. :roll: