Recently brought in a Dell
I can speak from recent experience at STI...
On July 3, 2008 I brought a Dell PowerEdge server (in original box) for use in my apartment in Santiago. I assumed I would be charged some import tax and so I was prepared with copies of the invoice and packing list to show what I had paid, in the hope of avoiding being overcharged.
Well, no one said one word or asked for a penny (or peso), to my relief.
I had brought in the monitor and printer on previous trips, also in original boxes. Only with the printer was I told I had to take it to one of the offices to pay taxes. However, since I could show that it was relatively ancient (over 4 years old) I was told there would be no tax. So, I was able to bring in a full-sized machine, along with a 20-inch flat panel monitor and a laser printer, with $0 tax.