iTunes Integration is still a bit flacky, for example mixvibes won't allow you to scan the BPM if imported from iTunes database rather than scaned from within mixvibes.
If you files are MP3's then they should work out of the box, however if they are m4a (aka Mp4) files then you need to install a directShow filter in windows, the best one I've found is the Core Audio filers:
http://www.free-codecs.com/download/Cor ... filter.htm