Majik,

Now I understand what's wrong!

When you type R, sdisk *read* the floppy disk and write a image file named 5501_1.out in your HD, overwriting the downloaded file with a image of the disk in your drive A.
To create the sampler disk, you must use W, to *write* the file 5501_1.out to the floppy disk.

As I said before:
R -> read floppy disk(source), write to file (destination)
W -> read file(source), write to floppy disk (destination)
D -> details are: name of the file, drive letter.

Mgomes