Nah I quit using those stupid cans of air. They get really expensive and didn't have enough pressure to blow the dust out of the last PC I tried to clean with them, let alone that heatsink. Bought a electric duster/vacuum combo for like £30 instead which lasts forever and doesn't have the moisture problem either. Obviously use the duster/blower, not the vacuum! Though the vacuum is great for vacuuming the car mats!)Christ, get some canned air on that thing..
@The VCR King if it's collecting that amount of dust in a week there's a problem! Is your PC sitting on carpet? If so raise it up a bit. I put mine some wooden blocks. Also make sure you clean your room - vacuum the room. You may be cleaning the wrong thing! (having a case with no holes in it helps too!)