Trivial case mod advice

I've never reshaped the metal in a case, but I need to make one change in my Antec P183 V3.

In general, this is a case used for quiet builds. But the included fans are known to be loud, and the top fan is held in place on one side with slip-in bent metal tabs ( http://www.silentpcreview.com/article945-page5.html ) . So I can't use silicone fan mounts for this one, and the fan case is in hard contact with the case.

How should I fix this? I'm imagining pounding the metal tabs back flat and then drilling holes for normal fan mounts. But what's the right way, or some of them?

Thanks.

EDIT: Can PWM fans be run on a Y cable?
 
Solution
You might Dremel-out that pinwheel, and use a silicone fan gasket between the fan and the case; it might be a tight fit under those metal tabs, but it certainly wouldn't rattle.
Get some painters tape and a 3/16" drill bit. Tape the top of the case for scratch resistance and mark out the four screw holes. Drill on a medium speed. This will create metal shavings so either cover or remove your components.
 
I'm going to go with the gasket in jtt283's reply. It's simpler for a newbie, and doesn't require cutting in a loaded case. I had been considering using my usual silicone fan mounts, but I would have had to put those tabs back in place and then drill holes in them (?). I didn't know about gaskets.

On the other hand, will I need two: one main one between fan and case, and one between fan and little metal tabs?

If the case were empty, I would have tried the drill. But I'm too lazy to take everything back out.

YARRGH - one of my plugins (Adblocker Plus, noScript, or DNT+) is blocking me from picking a best answer!
 
Thanks.
I don't know if a "double-layer" of gaskets could fit, but you might wedge a nylon washer under each of the tabs.
On the subject of PWM, the Arctic Cooling PWM fan I have has something similar on it, for the purpose of controlling two fans off of one header. I don't know if the Rosewill PWM fan I'm about to receive has that or not; hopefully I'll find out later today.