Soundproofing?

[Quzar]

I'm planning a bit of a project where I'm going to convert some old furniture into an isolated computer enclosure. I've got my main PC sitting by my entertainment center and get an annoying amount of noise from it both acoustic and EMI (gives a hiss on my speakers). What I figured is to put my machine (well two actually) into this thing (which is basically a wooden box) and set up the innards to both insulate as well as optimize for temperature and noise (ducted exhausts etc.).

So my plan to deal with EMI was basically to glue some mildly crumbly tin foil along the entire inside. According to what I've read that should block a good bit of anything coming out the case. The soundproofing is turning out to be trickier. There are plenty of real nice solutions designed just for that, but they tend to cost quite a bit more than I'm looking to toss at this. At first I pondered using ceiling tiles. My house was entirely drop-ceilings at one point, and I've got stacks of both gypsum and fiberglass(cotton candy type) ceiling panels. The big problem is that both of those are thick and relatively dirty (they shed).

What I've figured might be a better alternative would be some solid foam foil backed (two birds with one stone) thermal insulation sheeting. Does anyone have any idea of how good this might be? It's closed-cell foam, which is of a similar structure to soundproofing (non-thermal insulating) foam. Can anyone recommend a material I can find at a local hardware store that might do a better job (without being unreasonably heavy, like filling a liner with sand)?

Thanks.

[Zealous zerotype]

http://mini-itx.com/projects/decobox/
that project might give you some steps in the right direction.

[hearld500]

http://www.dynamat.com/

This stuff is amazing, I used it in my vehicle doors around the components.

Adhesive on one side and tin foil on the other so it'll probably help with the EMI too.