Are you just trying to import files from storage media to a new version of iTunes on a new PC or are you having issues with doing a sync of your music files among mobile devices and your computer?
I don't have personal experience with this, but for doing the latter, some of the articles I have seen imply that making it work properly involves some significant tweaking of the mobile devices - fun maybe for techies, but probably not so fun for people who just want to sync their music without accidentally wiping files, and move on. There are probably people around here who can do it and help you, but if not, and you have iPhone, iPods, and standard laptop or desktop computer that you listen to music on and want to sync among all your devices, you might want to just consider licensing a 3rd party commercial app that will handle this in a friendly fashion.
By way of example,
this one seems to have good reviews for transfer of music files among the 3, and it costs ~$20 and has both MacOS and Windows versions for the PC side.
I will stress that I do not have any personal experience with this or any other similar apps, and there seem to be a fair number of choices among for purchase applications for consumers, to do this task.
-Skylark
