Prepare External HD For New iMac

Technically, I'm a re-switcher. I had an iMac in 2011/12. Had to sell it for financial reasons during a horrible 8 month work-layoff. I'm back on my feet and getting a shiny, new late-2013 27" iMac in a few weeks. I've been using Windows 8 on a PC the last year and a half.

So, I have two 3TB external Western Digital MyBook harddrives. I've backed up all my files, pictures, videos and music on one. Both are formatted to NTFS. Should I wait until I get the iMac and format the empty one to Mac OS Extended or is Fat32 OK?

Any advice appreciated! Thanks in advance.

Format it to Mac OS Extended Journaled. You would be limited with FAT-32 to a single file size of no greater than 4 GB and would lose 1 TB of space on that drive because of additional FAT-32 limits on total size.

Many thanks. I will wait for the iMac and format then. Much appreciated!