Format NTFS and select default allocation unit size. This is best for home PC use.
Other sizes are usually only beneficial for specialized applications like SQL servers or storage arrays.
I'm mostly looking to use this as a gaming and higher speed drive for resource hogging programs like Photoshop or Mixcraft, if that makes any difference in comparison to a regular "home PC".
EDIT - I just found a thread on another forum about 4kb to 64kb, and it stated there was no discernible difference between the two. I appreciate the response, however.