What does your price include? Is it just the tower, or do you want a keyboard/mouse/monitor too? Do you want to include the price of xp in that($85usd)?
Point being, some people say computer, and they mean everything, tower, os, peripherals, etc, and others only mean the motherboard, cpu, ram and video card. My definition is a tower: a case, psu, motherboard, cpu, video card, ram, dvd drive, hd, fans, and the xp cost.