Something to note is that the smaller heatsinks do come with a permanant adhesive for the heatsink. If you choose to follow this route, remember you will not be able to correct it later. Then again, it shouldn't hurt anything at all if you add a heatsink to a card that did not come with one.
MacBook 2GHz Intel Core 2 Duo w/ 2GB DDR2 RAM & 120GB SATA 5400RPM HDD
Canon Rebel XTI
Google Cr-48 Beta Laptop