I often have to transfer large files >50GBs sometimes >100GBs between drives both internal and external during backups of our networks email servers. What is the best method of transferring these files? Command Line such as XCOPY? Possibly something robust enough to continue the transfer if interrupted due to time limits or network issues.
Check out robocopy. From Wikipedia:
robocopy, or "Robust File Copy", is a command-line directory replication command. It was available as part of the Windows Resource Kit, and introduced as a standard feature of Windows Vista and Windows Server 2008.