Hi,
The CFM rating of fans are often not very accurate, and to get a better judgement, you want to look whether your using 60, 70, or 80 mm fans, and the rpms they run at.
Pretty much any decent case will have the area for one 80mm exhaust and intake fan, and most midi or full towers have up to 4-6 intake and exhaust fan locations. Any generic 80mm fan will do, doesn't have to push much or or be loud, just as long as they work. I'd go Coolermasters or Panflo's for 80mm fans, cheap and quiet, and generally just get the job done.
