As far as I am aware spindoctor, the files you move from USB to USB won't be stored by the Windows OS on your HD, that would be most inefficient. There may be a record involving some metadata as a system record, but there shouldn't be actual files stored. I'm not 100% on this, but it makes sense.One thing to watch for, if you're not using flash memory, but a external HD instead, is that if you're using this and you delete your stuff, the OS definitely makes a record of this because the files wind up in the recycle bin (not the files themselves I hasten to add, but there is a pointer to the file on record in case you want you "undelete" the file). The file is still on your HD, albeit it may get overwritten, but a record is made by the OS on the HD. Best thing is get a 'file destroyer' overwriter piece of software and run it from the HD to wipe anything you want to get rid of on the HD.