Thanks for providing a few more suggestions. I have no idea how much the solutions sound coat offer are, but they look like a little (a lot) more than what i want/need.
I did a quick google for grommets and found some cheap kits... i'll have to look at them some more... otherwise i think i'll just glue them as it was also suggested, or use double sided tape. I need to find out how well either will hold up (long term).. the double sided tape might reduce vibration since theres no contact between case and fan, and the pad itself should make a good dampener... but i'm thinking it might not be strong enough to keep the motor from vibrating on its own if the fan has a little give...
I'm still strangely suspicious of the screws and the screw settings as well. Since when i take the fan out, remove the screws and hold it in my hand theirs very little noise coming from the motor.
I'll try both out soon. See which one I like. Whats the best way to dissolve the glue if I dont like it? Nail polish remover? Run a hair dryer over it?