If you think you will zwift a lot, I think the plan of getting a dedicated box is a good one. After trying out zwift for a few weeks on a macbook air in the early zwift beta days (it worked, but at low res and drained the battery down very fast), I decided to go all in and got the alienware alpha that they were recommending at the time and have been very happy. The alpha does the job very nicely and it is nice for me to not have to move a laptop around when I want to zwift.