That's always an option. There was a time that one needed a tower just to be productive, but these days, even the least powerful machine is 100s of times more capable than those "old" towers.
You may still need a tower if your doing more than the average home user. These machines much more powerful.. but apps require more to run and file sizes are getting bigger all the time. I was in a studio the other day and they were batching out 200+ photos from a 39 MP camera.
True dat.. which is why I initially said he should sell his old tower for a Mini. But then $100.00 for a tower isn't that much... better to keep it and come up with the extra 100. Not to mention avoiding packing/shipping that sucker.