You will probably need a quiet 80mm fan to help cool the chip. Some people wedge a fan next to a PCI slot to blow directly down onto the heatsink. I bought a Zalman FB123 fan bracket, so I have a quiet fan pointed perpendicular to my video-card heatsink. There is also a way to build your own fan bracket using a PCI slot cover, but I'm not sure of the exact procedure. Someone posted some instructions along with a couple pictures of their PCI slot cover bracket, but I can't find the post. Maybe another SPCR member can help find it?
MikeC himself did it in his article about OC'ing a P4 1.6 to 2.0. Here's the pic: