In my opinion it is foolish to use a Windows formatted drive on a Mac computer. The only reason for having a drive formatted for Windows if you are using a Mac as your main system is if you have other systems that run Windows and you need to transfer files using an external drive (And you haven't set up proper file sharing over your local network).
The first thing you should do when you get an external drive is format it for the type of computer it is going to be used on. NTFS for Windows, Mac OS Extended (Journled) for Mac OS X and FAT32/ExFAT for a drive that will be moved between the 2 different system.
What you should do is get another external, Format that to the Mac format, Copy all the data off the Windows formatted drive to the Mac formatted drive then format that second drive to the Mac format. All your problem will be solved.
I agree that it can be foolish to use a windows format on a mac. I was travelling abroad with a windows laptop for photography downloads and that is how I ended up with this drive. I was hoping that there may be another process other than that you mentioned. Thanks anyway.
Sure you need a utility that allows Mac OS X to write to NTFS formatted drives.
TUxera is a utility that gets round this Mac limitation.