Yes, save the files as wav. files in a seperate folder. Then open iTunes and change the import preference back to AAC (which is really m4a) EDIT PREFERENCE IMPORTING ( as per previous advice)
Choose add folder to library. When all songs are in the library hit Ctrl A on you keyboard to highlight all the songs -- then right click the mouse and select "Change selection to m4a" -- all songs will be converted to m4a.
Now delete the folder in Windows where all the wav files are saved.
Or you can just delete the songs from the iTunes library and delete the folder at a later time.
Note iTunes uses it's own default folder to save songs -- you can change this by going to EDIT PREFERENCES ADVANCED -- CHANGE.
