case filters for computer

Hey guys im getting a new pc soon and i was wondering if there was such a thing. Filters to keep dusts and insects outs. I got a few small spiders in my room and ive seen a few in my pc i got them out but i dont want something to get in my new pc plus no dust will help. I just dont know where to look. I saw a few on newegg but it has a size i dont know my case fans size but is there filters that i can put on my pc to keep things out? like on the case where the holes are?

only sites i can use is newegg or tiger direct the ones my dads uses.

thanks guys

If it's bugs you're worried about... don't worry. They'll get in regardless.
Dust requires cleaning. This may be once a month (lots of dust in the room) or even down to once a year (bare minimum really).

Which case do you have?

ive no clue which case it is. still waiting for them to ship the pc