Personally I would avoid using NTFS directly in that way. It is a proprietary Microsoft format, and who knows whether Apple received all the information from Microsoft when they implemented their drivers. One little corruption could see you lose all your valuable files.
If you can afford a new Macbook, buying a new 4TB external drive and formatting it Mac native would add very little to the overall bill. And give you native Apple format external drive. And keep the old drive as a backup. Plus, you could mirror to the other drive every now and again (manually) as you collect more valuable files.
Thanks for the input.
Ok, so buying a new drive isn't a problem but my question is... let's say i buy a new external drive and connect it to the Macbook. How do i transfer my data from my current 4TB Hitachi drive to the new 4TB Mac Compatible External Drive?
I'm trying to wrap my head around this - a simple drag and drop?
Thanks
If you're getting a new drive, you can set up a network SAN with a small linux board or commercial NAS solution (they are usually not *that* expensive). You can copy the files to multiple 2TB FAT32 partitions using a linux boot disk, then reformat the 4TB drive to HFS+ and then copy them back using OS X. At that point, I would set up the "spare" drive as a redundant backup or time-machine store. Both operations are simple drag&drop (the first in linux, the second in OS X)
As for long-term NTFS usage in OS X: it varies. My room-mate tried NTFS with his external for a while and had some issues copying to my NTFS external (only about half copied each time. OS X is such a great OS with respect to file copy, if it hits a single IO error, instead of trying to recover, or even fail gracefully, it throws up it's hands in frustration, stomps off into the corner and gives up completely at the first sign of trouble. How people can use it for a long period of time is completely beyond me) but was able to use it for his own files for a while without too much trouble. Up to you.
Another thing to try is to install windows to a flashdrive or something using refit, and using that to do the copy. Just quit using it before it yells at you to actually activate it (3 to 30 days, depending on version). This would be a bit more feature full (linux drivers for HFS plus are flaky, and hard to use) and significantly harder to set up, but partitioning and formatting would be familiar.
As far as actual filesystems, I prefer journalled ones like HFS+ or EXT3 to NTFS or FAT but haven't had any file loss or corruption from either (though my multiple redundant backups do help)