Read only on external hard drive

I have an external USB hard drive connected to my Macbook. The drive used to be in a PC but I had to get rid of it, so I bought an external USB hard drive enclosure so I could keep all my files. Now when I have it connected to my Mac it shows up and I can view and copy files from it, but I can not write to it. How can I change the permissions? When I click Get Info and look under Ownership and Permissions it says "You can only read".

The external drive is formatted in NTFS (the current standard Windows filesystem). Mac OS can read but not write to NTFS volumes.

If you have enough space on DVDs or your other HDD(s) to temporarily store everything on this disk, you could:

1. Move all the files off the NTFS drive.
2. Reformat the drive (FAT32 if you want it to be accessible by Windows machines, Mac OS Extended/journaled if not).
3. Move all the files back to the newly reformatted drive.

Oh crap. I would need a LOT of DVDs to do that. Well, thanks for the help anyway!

You could also move some/all of the files to your regular HD. Even if it took up a lot of space, it would only need to sit there until you could reformat your external drive and move them back. So if you have 50G of free space on your HDD, that would save you from burning 10 DVDs.

If your new external drive is huge, though, yeah, you're in trouble.