How to write to a Windows formatted disk from OS X? I have 4 external hard disk formatted on Windows as NTFS, but they are lying unused since I bought a Mac. So I am looking forward somehow I should be able to write to those disc without having to format them! Is there anyway I can do that?

I also tried NTFS-3G but it is giving me this error!
Paragon NTFS or Tuxera NTFS

Paragon NTFS and Tuxera NTFS will let you read/write NTFS partitions on OS X. They integrate with Disk Utility as well, letting you erase and partition such disks.