Mods to quiet down my PC...

Hi I was looking for advice to mod my PC case to keep it quiet. Particularly, I want to stick some type of insulator/fabric to the inside of my PC case to keep it from rattling. The aluminum casing vibrates very well, and the sound seems to sort of echo inside the case. I don't see why more cases don't come with this, as I'm sure it would help alot. I'm sitting here with a SonataII here afterall, a case built for quite PCs. Unfortunately, I've been browsing around the web and it seems those materials are way too expensive. Some look pretty nice in the $20 range like this:

http://www.frozencpu.com/products/3039/noi-02/FrozenCPU_Noise_Dampening_Material.html?tl=g7&id=QCLF7tSM

I don't really have any experience with this so I was wondering if anyone could recommend me some of their alternatives. In the best case scenario, I just want to go to Home Depot or Michael's to pick up some cheap material and duct tape it to my casing. Anyone know what type of material I should get?

Vibrations don't come from the case itself, they come from moving components acting on your case. Some little rubber grommets will likely do the trick to keeping vibrations pretty much null.

You could even cut them yourself using old rubber if you want to save money - or you could buy them, if you'd prefer an exact fit and all that.

I have found in the past the the sticky acoustic dampening "material" is next to useless expecially in a gaming rig and only really serves to increase ambient temperatures inside the case.

What RayvinAzn suggests is probably your best course of action. The most noise in a PC tends to come from fans. But the hard drive can make a racket as well especially a 10k drive such as WD's Raptor. Buying some rubber washers (grommets) and positioning them between the HDD and the housing will reduce all HDD produced vibration but it won't stop the noise of the HDD itself.
You can also use rubber insulators on your case fans as they will vibrate as well. Just place them inbetween the case and the fan and then screw them down.

Unfortunatly gaming PC's are not easily silenced. The only other way of significantly reducing noise in your computer would be to get a water cooling system and a passive PSU. That way, instead of having a fan on your processor, a fan on your graphics card and fans all around your case, you can replace them with water blocks and a reservoir of coolant. Then you just have 1 fan (usually a 120mm quiet fan) that cools the reservoir.
The passive PSU wouldn't have a fan to produce any noise so again that would provide a noise reduction.