You should definitely take measures to protect your gear — it’s not just the static electricity! Your desktop’s intake vents are like a vacuum cleaner, sucking up cat hair. Also, the cats are probably curling up for naps next to your warm, cozy CPU
, which just amplifies the problem.
I’ve heard of people taping stuff over their intake vents, like used dryer sheets or pantyhose. The danger with stuff like that, though, is you might end up obstructing air flow to the interior of the case.
I’d go to a hardware store and ask about spun fiberglass air filters; you’ll probably be shown something intended for use with air conditioners, but you could try cutting it up and taping it over your intake vents. At the same time, you can try to “caulk” up any other open spaces in the case (eg, the CD tray) as much as possible.
Your portable gear (notebooks, etc) should be better sealed, but I’d hit them with compressed air now and then to prevent build-up.