I don't have a problem with using a card or an external drive. I load my music to an sd card, then play it on the S3 with the Music Bee program.
I use an external drive for larger files - photos, documents, etc, - by plugging it in, opening a new window (one for the S#, one for the external) and just drag-and-drop from the S3 to the external. The external is also used on my (Acer) desktop so is compatible.