15 years old. It runs Win 95 and is used to build a version of one of our products that stops shipping this summer. It uses a 3rd party control that cannot be installed elsewhere as the vendor has gone out of business and the product has an aggressive anti-copying mechanism.

It was the only machine remaining that could build the product (the others died or were upgraded by mistake over the years), and the replacement 32-bit product ended up being 5 years late.