NFTS is a very strange beast. The filing system could even have multiple data node in a single file. This is the way it is able to properly serve Mac Files. It actually stores both the data and resouce data.

Interestingly this very feature was exploited in IIS3 as a method of hiding extra data in a file. If I remember correctly adding :$DATA$ on the end of the file accessed the primary data node :$XXX$ accessed the alternate node XXX. Due to its use to hide porn this feature was service packed in IIS.

Without special tools a file would appear 1k long to the OS but would take 10min to copy from disk X to Y. The copy from NTFS to NTFS copied all the data nodes not just the one the OS reported. The secondary node may have been 10Mb but completely hidden and a right pain to find if you were the sysadmin on a shared web hosting site.

Just a bit of digression
UnderMine