Using a vacuum to clean dust from a case is very risky business. We have seen a large number of computers destroyed over the years from static electricity created from vacuums.
The safer choices are some of the canned air that you can buy at any good shop, as well as Wal-Mart, BestBuy, Circuit City, CompUSA and so on. We like Dust Off with its propellant of difluoroethane gas, as it works best, lasts longer, and is very safe.
You will find the infestations to be more frequent if you have dogs and cats, or new carpet, or if you smoke. Putting your CPU on the carpet is risky. Elevate it at least three inches, and more if you can. The higher the better.
We also recommend a Q-Tip and denatured alcohol, along with a alcohol-moistened paper towel to remove the stuff that sticks.
Finally, despite the nose, extra case fans are worth the few dollars they cost, just because of their effectiveness in keeping the dust and fiber down.
