Harmy, transferring between two internal drives over SATA is the optimal approach, but barring that being available to you, USB3.0 (if connected to a 3.0 port) is up there in speed with eSATA (also a good option, if available), so working between system drive and USB3.0 drive should be adequate. Where the most disk I/O is occurring is what you'll want to have the quickest access to, assuming most of the work being done is processing on the source files and the destination is mostly for outputting the result, then you'll want the source files on your local system drive, and let the output go straight to the external disc (and its far better than processing files and writing the output within just a single disk drive, the seek time would get crazy and you'd frag your disk much more than necessary). Location of the exe, .bat and .avs probably don't matter a whole lot, either, as they'll probably be running mostly from RAM anyway.