That's a beautiful machine. Would love to be able to pick it up from ya.
Back before I got into Amiga, my grandfather had an Atari 520ST. He had some CADD program he used for work, GFA Basic, and some games, both commercial and freeware. I really got into that machine, and have wanted to get my hands on a 520 or 1040 model ever since, or even something more like what I use in Amiga-land. I was promised his computer and software collection upon his death, but it went into another relative's closet and hasn't been seen or heard from since.
The desktop aside, the Atari ST is a neat computer. One day when I can justify the expenditure, I'll pick up a unit to learn and play with.