One of the most common support issues relates to establishing proper file sharing and user permissions at the operating system level. A useful link in this regard is: How to configure file sharing in Windows XP

While XP Home works on smaller networks, note that simple file sharing is the default and cannot be turned off. Typically with XP Pro you will want to turn off simple file sharing by clicking on My Computer then choose Tools then Folder Options and then click on the View tab and at the end uncheck "Use simple file sharing." This will create the NTFS partition. For more information, see the link above and consult with your IT professional before making changes of this nature.