Dust preoccupation

i got a brand new computer. it is awesome. it has cool lights and a lot of fans. its my bebe.

i heard that dust is bad for computers, it makes them warmer and shorten it life duration.

as soon as i herd that i cleaned my whole room away from the dust. one week after i bought it, i look inside the case's window and i see a fine mist of dust covering the insides of my computer. it is really thin tho, you cant see it without strong light.

so..
1. is it true if i put pantyhose over the draw-in fans there will be no dust coming in my computer?
2. if yes, then how do i make the pantyhose stay in place? is rubber tape o.k.?
3. am i worrying too much or i really need to use the dust-off now?

I use some pantyhose on my intake fans. After a month or so they have a layer of dust that I vacuum off so they definitely do stop some dust. I still get dust in my case and clean it about once a year though. I removed my fans, chopped the pantyhose into a square then stretched it over the fan assembly and kept it in place with an elastic band. Afterwards I screwed the fan back in place on my case driving the screws through the pantyhose to keep it in place allowing me to remove the elastic bands.