Originally Posted by JennyT
I'm not a computer programming person, so I guess I don't understand why it is difficult to make calibre recognize Kindle Fires on an XP machine.
XP was tested in the beta of calibre's MTP implementation. Since MTP support wasn't in the original release of XP the solutions to this were hit and miss. It is not a matter of fixing it in calibre it is a matter of XP not properly supporting MTP.
Currently calibre supports MTP for Windows Vista and newer Windows versions and Linux. Windows XP and Apple's OSX are not supported because of limits within the respective OS.