You still haven' t really told me what's on the drive. "iTunes" refers only to the application, not your library, and a library is more than media files. A complete library is everything in the iTunes folder which includes special library files, artwork folders, and various other files and folders. The library files tell iTunes what to show you and how when you open the application, otherwise all you have are a bunch of media files on a drive and not really "iTunes".
What are the iTunes library files? - http://support.apple.com/kb/HT1660
More on iTunes library files and what they do - http://en.wikipedia.org/wiki/ITunes#Media_management
What are all those iTunes files? - http://www.macworld.com/article/139974/2009/04/itunes_files.html
Where are my iTunes files located? - http://support.apple.com/kb/ht1391
You can play a file on NTFS, for example in Quicktime Player. However, if you have your library files on the drive, you want to start iTunes from them, then you do anything at all in iTunes such as try to play a file, iTunes needs to re-write the library file with the updated play count information but can't since it can only read NTFS, not write. Then too if you wanted to change the artist name a bit on a track iTunes will need to write the change to the library file as well as the media file, but won't be able to do either with NTFS unless you install special software enabling NTFS (which isn't ideal).
Standard recommendations in this scenario are:
1) If you need to use the drive with both Mac and NTFS then buy software for either the Mac or the PC which enables using the other platform's drive format. Alternatively if none of your files are bigger than 4GB you can use FAT format (still some disadvantages with Mac use).
2) If only for Mac use, store the files on another drive temporarily and reformat the drive to Mac Extended (which erases the drive) using Disk Utility.