Using this technique is fairly straightforward, and easily adapted to cut almost any type of hole in your computer. Most of all its cheap - but still produces professional looking results (when a little care and some time is
taken). You can cut the metal grill from the front of your case or even create a blowhole in the top or sides of your case. Use the drill to create an outline of many holes, punch out the outline of your blowhole and use the drill-grinding stone combo to clean it all up. It's also a good idea to attach a finger guard when you screw your fan on - this should help stop any stray items from making their way into the fan.
FULL STORY @ OVERCLOCKERS (http://www.overclockers.com.au/techstuff/a_case_cut/)