Erm, a drill? If you've got a plastic case, then use a drill bit for metal in a hand drill (power-drills run too fast), if you've got a metal case then a power-drill is fine. You'll need to drill 4 bolt-holes to mount the fan, and a grid of 4mm holes to suck the air through. If the grid of holes is not to your taste, then drill a circle of holes very close together, the diameter of your fan-blades, punch out the centre section, then file the edges smooth. Get a chrome grid to protect your fingers from the blades. Mount the fan, and you're laughing guv!