1st - I guess it should be mentioned that you only need to FTP into XAMPP from a remote machine. IF this is obvious, then excuse my being a bit pedantic, but I have explained this several times before, only to find folks didn't know they could move thing locally just fine with Windows Explorer.
For the next item, I am presuming you meant you have installed the FileZilla Server
2nd - You just create a user for XAMPP in your original FileZilla server install and make that user's Home Directory (Shared Folders)be \xampp. Be sure NOT to start FileZilla in teh XAMPP Control Panel, nor (sic) to make it a service.