Just a tip, if you want to go through the ordeal a lot less frequently:
Get a metal grid (same diameter as the fan) and a thin/lowdensity filter, and then:
1. Take off the screws going through the fan into the heatsink.
2. Fit the grid over the fan's screw holes (yeah, we like screw holes, don't we? ;)
3. Fit the filter over the grid.
4. Force the screws through it all, and into the heatsink.
Just make sure the filter lets through enough air, you can test-run it by monitoring with Speedfan/similar - have the case's side panels mounted for accuracy.
